Ben and Polly are stunned at what they have just witnessed. The Doctor - the old man they have known and trusted - has changed his appearance right before their eyes. He has seemed to collapse and "die", only to be "renewed" as a totally different, younger man. The two young people stay near the door, unsure what to do. Their world is now upside down. The TARDIS - which had been acting strangely as well - at least seems back to normal.

They try to keep their fear in check in the face of this bizarre situation. Polly wonders what they can do to help the Doctor, but Ben wrestles with a more basic problem: is this really the Doctor? Polly thinks it must be - no one else entered the TARDIS and the old Doctor said something about his body "wearing a bit thin". But it seems impossible to Ben that he could just trade his old body in for a new one.

Suddenly, the man on the floor begins to stir. He tries to focus on the two faces above him, but his vision swims. He holds his head and tries to concentrate, a searing pain rushing through him. After a long and agonising moment, the man - the new Doctor - announces gratefully, "It's over."

The Doctor stands, steadying himself on the control console. He operates the controls and the familiar sounds of dematerialisation fill the room. Ben finally ventures to speak, but the Doctor does not respond. Ben's mistrust of this seeming stranger is renewed. The Doctor staggers unsteadily, grabbing the console again. As he does so, his jewelled ring falls from his finger and clatters to the floor. He ignores this and turns his attention instead to his clothes. They, too, seemed to have changed. Beneath his cloak, the new Doctor wears a sloppier, baggier version of his old clothes: no waistcoat and no cravat, but a baggy jacket and checked trousers with a ratty bow tie, askew and barely hanging on. He looks like a hobo or a tramp.

The Doctor spots a storage chest sitting in one corner of the console room and he hobbles over to it, complaining that his muscles are still a bit tight after the change. He begins rummaging through the chest, saying nothing. Polly and Ben watch him, dumbfounded. Has he even noticed them? Polly clings to her faith that this is the Doctor, but Ben is more concerned as this stranger certainly doesn't act like the Doctor.

Ben decides to confront him, but the Doctor has other ideas. He shoves a square-framed mirror into Ben's hands. The Doctor gazes into the mirror, seeing his new face for the first time. Before his eyes, though, the image changes to that of his old face. He is confused and somewhat frightened for a moment, but then his vision clears and the proper image returns.

Forgetting the mirror and his companions, the Doctor begins rummaging in his pockets. Ben, angry at this treatment, demands to know what this stranger is playing at. The Doctor finds an ornamental dagger which he says he got from Saladin during the Crusades. But he refers to "the Doctor" in the third person as he does so. This gives even Polly a start. The Doctor himself now seems unsure of his identity... and theirs. The Doctor finds a piece of grey metal in his pocket. His face contorts in fear and he mutters a word from his past: extermination. Moving on, he next finds a magnifying glass with which he examines his hands. He says he will be happier when his nails have a chance to grow.

Tired of watching all this, Ben tries again to confront the man. He picks up the old Doctor's familiar ring from the floor. He thinks that if this man really is the Doctor, the ring should fit. A test finds it far too large. Stung by the implied distrust, the Doctor likens himself to a caterpillar which has emerged from a chrysalis case as a butterfly - the same, but different. This seems enough for Polly, but Ben is still sceptical of the Doctor's claims of "renewal". The Doctor says it's "part of the TARDIS". Without it, he would not be able to survive. Then the Doctor is back in the storage chest, looking for his diary. Ben decides to give Polly the benefit of the doubt for now, but he still worries about what this "change" will mean for them.

The Doctor finds a recorder among several other items in the chest. Gleefully, he blows a little tune, doing a jig along with it. Adding the recorder to his pocket, he digs in the chest and finally finds the book he's looking for - a 500 year diary - and flicks through it, wholly absorbed.

Polly ventures the question of what will happen to her and Ben, but the Doctor changes tack on them again. He is sure the TARDIS has landed and is interested in going for a stroll. He pulls a stove-pipe hat from the chest and puts it on, unaware of how ridiculous he looks. His attention still fixed on the diary, the Doctor opens the TARDIS doors and starts to walk out, seemingly oblivious to any of the readings on the console. However, unnoticed by his companions, he has taken keen note and rattles off the numbers to them as he walks outside, his nose still buried in the book. Perhaps there is more to this seeming clown than meets the eye. He beckons them to join him, mentioning Ben by name. Polly is cheered - at least he knows who they are.

The TARDIS stands in a grey, rocky landscape. A solid mist hangs low on the ground, fed by bubbling pools of silvery-grey mercury which erupt at irregular intervals. Through this virtual minefield, the Doctor walks heedlessly. His attention is seemingly lost in the diary, but he still manages to avoid stepping directly into one of the pools. Laughing at an incident recorded in the diary, he calls back to his companions, continuing to move forward.

Finally his attention is drawn out of the book when a large rock blocks his way forward. He could go around it, but decides instead to give his new legs a bit of a test. He sizes up the boulder and then makes a running leap, springing easily over it. He is very pleased with his agile new body.

Nearby, an older man in a sort of jumpsuit wanders, clearly lost. He is calling out as he goes, sounding quite put out. Moving through the mist, he catches sight of the Doctor. Thinking this at last is the welcoming committee he's been looking for, he moves forward to greet him. However a gunshot rings out and the newcomer collapses dead at the Doctor's feet.

The Doctor goes immediately to the man's aid, but it is far too late. He examines the man's ID badge, finding his old spectacles useless with his new eyes. The dead man is an Earth Examiner, accorded all access on the colony planet Vulcan. The Doctor looks for more information in the man's pockets.

Unseen by the Doctor, another figure approaches. This one wears a silver suit and a full helmet with visor. He moves quietly and is armed with a small rifle - the weapon which killed the Examiner. He attempts to move in on the Doctor, but is forced into hiding when Ben's voice echoes nearby. The Doctor senses the movement but not its location. He is wary. The helmeted man fears it will not be long until he is discovered. He must act quickly.

Ben and Polly move much more slowly and carefully than the Doctor. They are not as convinced of the strange planet's safety as he seemed to be. The heat is stifling. Polly stops to examine one of the mercury pools, Ben warning her to be careful of the dangerous mercury. Ben turns away for a second, looking for the man who may or may not be the Doctor, just as the pool erupts in a silvery spray. Polly takes it full in the face, coughing and sputtering violently. Then she falls unconscious. Ben tries to help her but cannot wake her. He calls out in desperation for the Doctor.

The Doctor stands in response to the call and moves in Ben's direction. Before he gets too far, the assassin leaps from hiding and clubs the Doctor with the butt of his gun. The man places a button in the unconscious Doctor's hand and then sets about removing the body of the Earth Examiner.

Ben tries to get Polly to her feet and away from the pool, but is hampered by her dead weight. Suddenly the pool erupts again and Ben is covered with mercury spray. He, too, coughs and sputters, dropping Polly. He falls to the ground beside her. His vision fades just as a white-suited figure approaches.

A group of white-suited men has arrived in the area - the search team looking for the real Examiner. They saw his ship overshoot its landing area - a not-uncommon occurrence here - and have just now arrived to search for him. One of the men looks over the Doctor. He is the colony's Deputy Governor, Quinn. He is small and middle-aged, a bureaucrat to be sure, but an earnest one. He stands as another member of the party approaches, taller and younger. This is Bragen, Head of Security. He is somewhat thuggish but very shrewd. There is clearly no love lost between these two. Bragen reports finding Ben and Polly unconscious by the pool.

Because of the ID badge the Doctor appropriated, Quinn believes him to be the Examiner. He is glad the Examiner is unharmed, but wonders with some aggravation why Earth has sent him just now. He isn't due for two more years. Quinn has little time to wonder about this as Ben regains consciousness and joins the group. Quinn is quick to make nice with "the Examiner's" staff. Quinn, Bragen, and the guards gather up Polly and the Doctor and prepare to take them to the colony.

As they start off, Bragen makes a veiled attempt to ascertain the reason for the Examiner's visit. He believes they are here to inspect "Lesterson's space capsule". Ben is a little lost with all this and says little either way. He is surprised to see the "unconscious" Doctor's eyes pop open for a second, wink at him, and then close again. He has been awake and listening for some time.

The space capsule in question is ensconced in the laboratory of the colony's chief scientist - Lesterson. It dominates one side of the room with it's dark dull/shiny bulk. He is absorbed in examining a piece of the capsule, nearly oblivious when his assistant - Janley - enters. She wants to tell him about the arrival of the Examiner. Both of them believe the Examiner is here to stop Lesterson from working on the capsule. Lesterson vows to continue, no matter what. He hasn't let the Governor stop him; this Examiner won't succeed either.

Janley, however, has another concern. She wants to use the old rocket room for a "meeting". Lesterson absently agrees. He deplores the "pressure group" she's joined, but she claims they are fighting for a better colony. They are rebels. She tries to tempt him with the promise of more funding and better facilities, but Lesterson has no use for politics. His single-minded concern is the capsule. Its metal has survived 200 years buried in the mercury swamp with no corrosion or any other damage. He is determined to unlock its secrets; politics, the Governor, and the Examiner be damned!

The Doctor, Ben, and Polly have been ensconced in simple quarters in the colony. All are conscious and well. The Doctor has told his companions a little of what happened in the swamp and how he came to be mistaken for the Examiner. But now he has stopped talking and only communicates through nods and shakes of his head while blowing a series of notes on his recorder. He refuses to return to the TARDIS and plans to go on masquerading as the Examiner for the time being. This non-communication finally grates on Ben and he grabs the recorder away from the Doctor. He still wants answers for the Doctor's physical change and an outright admission that he is really the Doctor.

Ben does not get the answers he wants, and shortly the conversation ends with a knock on the door. Bragen enters, escorting Hensell, Governor of the colony. Hensell extends an apology to "the Examiner" for his landing error, but blames the surprise arrival. The Doctor plays his assumed role to the hilt, refusing to reveal his reason for coming (as if he knew it at all) and intending to begin his examinations at once. As the Governor and Bragen try to prod him - suggesting both the "rebel groups" and Lesterson's space capsule as the reason for his arrival - the Doctor seems more interested in examining both men's jumpsuits.

The conversation centres on Lesterson's capsule, Hensell explaining that it was buried in the swamp for centuries. He thinks it may be dangerous due to foreign bacteria or some such thing. The Governor seems relieved that "the Examiner" is interested in the capsule. He has failed to stop Lesterson's work and perhaps the Examiner will succeed. And besides, he is secretly worried about the increasingly troublesome rebels and is glad the Examiner seems to have little interest in them. Hensell says - a bit too cheerfully - that he looks forward to his report on the capsule. He and Bragen take their leave.

Once they're gone, the Doctor settles back with his recorder (secretly retrieved from Ben) and falls into deep thought. Ben and Polly realise that the Doctor was checking the men's suits for evidence of the missing button, but he also reveals that he was watching Bragen to see if he was as concerned over the space capsule as Hensell seemed to be. No matter, though, the Doctor wishes to examine the capsule soon. But Ben is worried the Doctor is taking his role too seriously. He may be able to pass himself off as the Earth Examiner for a while, but he will not fool the person who killed the real Examiner!

Some time later, as evening begins to fall, Deputy Governor Quinn tracks down Bragen in a corridor. Quinn is furious because Bragen's guards are posted on the Examiner's quarters and have refused to let him in. He is certain it is Bragen's doing. Calmly, the Head of Security explains that it was the Governor's idea to protect the Examiner. His quiet smugness further infuriates Quinn and he stalks off.

Quinn collides with Janley as he turns a corner. He apologises, some of the anger leaving him. Janley face is full of concern - Lesterson has cleared her out of the lab in honour of the Examiner's visit. She is concerned that Lesterson's planned opening of the space capsule may be scrapped. Quinn is heading to the laboratory now to see if that is the case. Janley continues on, noting to herself that Quinn's uniform sleeve is missing a button, but not knowing what it might mean.

In the lab, the Doctor is examining Lesterson's space capsule and questioning the scientist. Ben, Polly, and Hensell look on. The Doctor appears deeply concerned. Lesterson tries to make the case that the capsule and its strange metal could hold secrets that may revolutionise space travel. The Doctor, too, is interested in the metal, but this is because it closely resembles the metal he was examining in the TARDIS earlier! Dalek metal.

Lesterson presses the case for opening the capsule, showing the laser torch he has already prepared for the task. Hensell defers to the Doctor, who agrees to the test. It takes two attempts, but Lesterson manages to trip the locking mechanism and the capsule opens. Inside is just a small, featureless entry bay. Nothing of any note at all. It is clear to all that there must be an inner hatch, but it will take Lesterson some time to find the locking mechanism and break through. The Doctor, however, has found the inner hatch already, unseen by any of the others.

The Doctor uses his "authority" to halt all further talk of entering the inner part of the capsule, at least for tonight. The Governor is none too pleased with this show of power, but he complies. The Doctor seems concerned about the obvious alien nature of the capsule and makes sure Lesterson understands that as well. Then he turns and suddenly leaves the room. Ben and Polly must hurry to catch up with him.

They pass Quinn on his way in. He is angry to have missed the Examiner again. Hensell and Lesterson engage in recriminations, each assuming the other sent for the Examiner. Quinn still wishes to talk to him, hoping to find out why he's here, but Hensell forbids it. As long as the Examiner is preoccupied with Lesterson and his capsule, he can't poke his nose into other, more sensitive problems in the colony. The Governor orders Lesterson to keep the Examiner occupied by whatever means necessary. He then leaves, along with a flustered Quinn.

Lesterson starts to return to work, but notices that the spare bit of metal from the capsule is now gone. Taken by the Examiner!

Later that night, Polly awakes in their quarters to find the Doctor gone. She sees the door closing and realises he's just gone out. She wakes Ben and the two of them decide to follow him, certain he is heading for the lab.

The Doctor makes a bee-line for the lab. It is empty now, but still faintly lit from Lesterson's work lights. The Doctor goes straight inside the capsule and to the inner hatch that he discovered earlier. Using the piece of metal that he swiped from Lesterson's work bench, he inserts it into a small slot in the capsule wall. It is a key and the "hidden" inner door slides open. Inside, as the Doctor had already deduced, he finds Daleks. Two of them. They appear dormant.

Ben and Polly arrive and the Doctor invites them in to meet his deadliest enemies. Polly realises that the Doctor has been way ahead of everyone all along, despite his bizarre behaviour. He still refers to "the Doctor" in the third person, but this is clearly the real Doctor. The man who has faced the Daleks before.

Ben and Polly believe the Daleks to be dead, victims of two centuries of submersion in a mercury swamp, but the Doctor is dubious. These are no ordinary creatures. With Polly's prompting, he has also found something else troubling. A thick layer of dust coats the interior of the capsule, except for one spot. The outline of a third Dalek casing shows on the floor. It is now missing.

Ben makes a move toward the creature and the claw retreats into the darkness. The Doctor sends Ben to fetch a work light from the laboratory. Polly is frightened, but the Doctor seems to take little notice. Ben returns with the light - a unit on the end of a long power cord - unaware that he is being observed by a man from the shadows.

The Doctor shines the light into the corner where the claw appeared but sees nothing. The creature is gone. He seems less concerned about this than about the missing casing. Jumping several steps ahead of his companions, the Doctor hurries out to the laboratory to search through Lesterson's equipment and papers.

Ben and Polly realise that Lesterson must have been lying about never having been inside the capsule before today. The Doctor believes he's removed and has been experimenting on the missing Dalek, but Polly is sure these Daleks are all dead. The Doctor assures her - with chilling certainty - that all the Daleks lack is power. Once they have that power, they will come to life and exploit the turmoil in the colony to destroy it. All it takes is one Dalek to accomplish this.

Meanwhile, Deputy Governor Quinn has gone to try once again to contact "the Examiner". But he enters the Doctor's quarters to find him and his assistants gone. A moment later, Bragen bursts in, reminding Quinn that the Governor forbid him to speak to the Examiner. Quinn quickly becomes angered at this insubordination and at Bragen's heavy-handed tactics. He refuses even to dignify the Head of Security's questions with a response.

Quinn goes to leave the room, but Bragen blocks his way. Quinn shows some surprising strength as he pushes the larger man away. He warns him never to do that again and calls for a security guard. A search must be made for the Examiner. Bragen is not unaware that Quinn is doing his job.

The Doctor's concern is contagious and soon Ben is recalling how the "real Doctor" used to talk about the Daleks all the time. The Doctor seems stung by Ben's continued scepticism, but he can hardly blame the lad. The Doctor is still trying to puzzle out how to stop Lesterson, certain it will be difficult to get him to listen. However, the Doctor gets bogged down in repeating the tongue-twister "Lesterson listen" to formulate a strategy.

Their conversation is interrupted when Lesterson bursts into the lab, accompanied by another assistant, Resno. He was the man who observed Ben earlier. Lesterson is, of course, hopping mad at this intrusion. The Doctor resorts to bluster, relying on his role as an Examiner to keep Lesterson at bay. The man's erratic behaviour doesn't wash with Lesterson, a man used to having his own way. But the Doctor turns the tables, proving that Lesterson had opened the capsule previously and already discovered the creatures inside. The term "Dalek" is unknown to the scientist and he denies that he removed the third one and hid it away.

Bragen enters and demands an explanation. Ben and Polly explain the Doctor's theory. Lesterson admits he's been inside the capsule, but he denies having removed one of the "Daleks". In fact, he is careful to tell Bragen there are only two of them. Ben tries to explain to the colonists the evil nature of the Daleks, but the Doctor stops him to avoid blowing their cover. But this allows Lesterson to insist they are only objects of scientific research and are completely harmless.

The Doctor demands - somewhat confusedly - the destruction of the Daleks, invoking his status as an Earth Examiner. Lesterson is certain he is exceeding his authority and the Doctor wishes to see the Governor on the matter. Immediately. He hurries from the lab, Ben and Polly in tow. Bragen follows, almost determined to keep the Doctor from his audience.

Lesterson stays behind with a worried Resno. But Lesterson has no time to listen to his assistant's fears. He sends Resno to fetch Janley, then locks the lab door. He goes to a secret compartment and opens it, wheeling out the missing Dalek. The creature is as dormant as those in the capsule, but it is clear that Lesterson has indeed been experimenting on it. His focus is far beyond simply learning about the creature. He is determined to bring the Dalek back to life, no matter what the Examiner says.

Bragen convinces the Doctor to wait in his quarters while he tries to arrange a meeting with Governor Hensell. He tries to placate "the Examiner", asking him to exercise a little discretion in his investigations due to the current political climate, but the Doctor is determined to see the Daleks destroyed. Even Bragen's concerns about the rebels - minor acts of sabotage, secret newspapers, etc. - seem to matter little to the Doctor as he becomes absorbed in examining a bowl of fruit which has been newly placed in the room. Bragen goes off to try and arrange the meeting before the Governor leaves on his tour of the perimeter in the morning.

Once they are alone, Ben turns on the Doctor. His preoccupation with the fruit bowl - as well as his other nonsense - has Ben once again believing that this man may not be the Doctor at all. Polly supports the Doctor as best she can, but he brushes both of them off and returns to examining one particular apple. From it he extracts a small electronic microphone, showing it to his companions with a smile. He smashes the unit with his shoe.

Ben is properly chastened, realising now why the Doctor was acting so oddly... in this instance. The Doctor seems glad to have the full support of his friends again, smashing another piece of fruit to make them laugh...and to destroy any remaining listening devices.

Ben is concerned as to who planted the device, but the Doctor looks toward a larger question: who murdered the real Examiner. Polly also wonders who sent for the Examiner in the first place. Surely not Lesterson - he only wants to be left alone to experiment. And the Governor would hardly want to admit he couldn't handle things here. Ben tires of the pointless conjecture and suggests returning to the TARDIS. But the Doctor refuses. Despite how they appear, the Daleks are not dead. The claw they saw proves that. The danger they pose to the colony makes it impossible for him to leave.

Later that evening, work has recommenced on the third Dalek. Janley and Resno have attached power leads to the Dalek casing. Resno seems a bit apprehensive, not liking the looks of the ugly Dalek one bit. Janley mocks his lack of scientific detachment. This makes Resno lash out at her, denouncing her alliance with the rebels and assuring her she won't succeed against the Governor. Clearly, Janley has been less than circumspect in her opinions. She turns on him, but Lesterson silences them both. He wants no part in politics in his laboratory and is in a hurry to get the Dalek working again before the Examiner can stop him.

Bragen returns to the Doctor's quarters with bad news: the Governor cannot see him tonight. He hopes they can meet in the morning before his trip to the perimeter. The Doctor refuses to accept this and tries to get out past Bragen. Bragen blocks him and reiterates his information. The Doctor appears to give in and Bragen leaves.

But the Doctor has another plan. He decides to put in a call to Earth and convince the authorities to back him up. Hopefully that will put an end to the Dalek threat. As he goes off, bumbling with the door knob, Ben and Polly watch amusedly. In some ways this is still the old Doctor, but in other ways he is a comical copy.

Meanwhile, Lesterson has begun feeding power to the Dalek. Resno monitors an instrument panel while Janley stands by with a notebook to monitor the effects of the power now surging into the creature. At first there is no response from the Dalek, and Lesterson determinedly increases the power. Shortly, the Dalek's sucker arm begins to move, followed by the eye-stalk. Resno is alarmed but Lesterson follows developments with seeming detachment. He moves forward to examine the Dalek more closely. The second "arm" is still dormant. Lesterson is unaware that it is a gunstick.

Janley jumps back in alarm when the sucker arm extends toward her, but Lesterson dismisses it as a "nervous reaction". He thinks the creature could have a primitive positronic brain. If only he could open it up, he might find a way to power it permanently...

Suddenly, the eye-stalk and sucker arm droop, as if the power was leaking away even though all instruments are still registering. Lesterson returns to his panel and changes some dial settings. Soon the eye-stalk raises again, this time focusing directly on Resno. His paranoia flares up again and he accuses the creature of watching him. Lesterson tells him tersely to pull himself together and get on with his work.

The Doctor enters the communications room to find it darkened and silent. Soon he sees why. The radio mechanic on duty has been knocked unconscious and the main cables to the communications equipment have been severed. He moves to examine the body but stops when he hears movement in one corner of the room. It is Quinn. He emerges from the shadows, looking somewhat sheepish and holding a pair of oversized pliers.

Quinn is glad to finally have a chance to speak to the Examiner, but he can say nothing before Bragen bursts in with a guard. Bragen clearly suspects Quinn of knocking out the mechanic and cutting the cables. He takes the pliers away as evidence. Quinn protests his innocence, saying he just picked up the pliers, but his story sounds suspicious. Whoever did this has cut them off from Earth completely. Bragen blames the rebels and seems to insinuate Quinn's involvement, sparking another row with the Deputy Governor.

The Doctor, however, has other concerns. He has noticed the button missing from Quinn's sleeve and now feels that he must say something. He tells Bragen he was attacked in the swamp after landing - the truth, up to a point - and produces the button as evidence against the suspected culprit. He also points out Quinn's sleeve. With this and the overwhelming circumstantial evidence here in the communications room, Bragen decides to detain Quinn, who remains defiant. There will be an inquiry before the Governor first thing in the morning.

In the lab, Lesterson has upped the power output to the Dalek. Renso now has a film camera pointed at the creature as the power goes on. The Dalek comes to life again. Lesterson is pleased as the creature's entire body moves, gunstick included. It turns to focus on Resno again, making him nervous. He backs away from the camera, frightened that the Dalek is "weighing him up".

Lesterson must physically move Resno back to the camera, barely containing his impatience. But just as Lesterson turns to go back to his instruments - and Janley is engrossed in hers - the Dalek weapon suddenly fires. Resno crumples to the floor. Janley races to his side as Lesterson disconnects the power. She quickly tells him that Resno's not dead, but neither of them can figure out what happened. Lesterson, fearing as much for his experiment as for Resno's health - races off to the hospital to get some help.

Janley begins destroying her notes to cover what has happened. Unseen, the Dalek's eyestalk moves of its own accord.

As morning dawns, the Doctor and his companions await the start of the inquiry. Ben is convinced of Quinn's guilt - believing he is trying to destabilise Hensell and take over as Governor. Polly thinks this ridiculous, going mostly on instinct that Quinn is innocent. The Doctor says nothing, playing his recorder and sinking deep in thought as Bragen arrives to take them to the Governor's office.

Despite the "accident", Lesterson has continued his experimentation all night. As morning dawns, he is giddy with the success that they have achieved, certain it will mean great things for the colony. Despite all this, he has removed the gunstick from the Dalek as a precaution.

He inquires of Janley about Resno. She has been gone for long periods of the late night work. She says she has seen Resno just this morning and that he will be fine after some rest. She strongly urges Lesterson to tell no one of the "accident", especially the Examiner. It would only give him more ammunition against the project. Lesterson agrees. Janley's spirit turns suddenly buoyant, energising Lesterson to head off to reveal their success to the Governor.

The inquiry begins with Hensell questioning Quinn. There is no hard evidence to link Quinn to the attacks on the radio mechanic or the Examiner, but the Deputy Governor cannot explain away any of the circumstantial evidence. Getting nowhere, the Governor changes tack and addresses the Doctor. The Doctor believes that the Daleks could be the motive for the destruction of the communications equipment. Someone wants their existence kept secret.

However, before he can comment further on this, Lesterson bursts in past the guards. The Governor is incensed at the intrusion but the scientist, bursting with pride in his success, will not listen. He promises to show them a development which will revolutionise the colony and then shouts to Janley outside. She enters, followed by the Dalek. The creature glides in on its own, silencing everyone.

The Doctor is appalled and angry. This should not have happened. The creature scans the room and its eye-stalk alights on the Doctor. The Doctor backs away, his face a mask of fear. The Dalek, too, seems to react to his presence. Ben swears the Dalek must recognise the Doctor, as crazy as it sounds. The Doctor agrees.

Lesterson is triumphal, knowing he has made the impression he had hoped for. He demonstrates that the machine can understand orders, making it push a chair. He foresees Daleks taking over menial labour jobs and ending the colony's problems forever.

The Doctor regains himself and tries to make the Governor and the others understand the evil nature of the Daleks. It will end the colony's problems because it will end the colony! Suddenly, the Dalek speaks. Its grating mechanical voice tells the stunned group: "I am your servant."

Governor Hensell is duly impressed by the Dalek's display of autonomy. Lesterson is floored, his mind reeling with the possibilities. They are joined by Bragen, visions of Daleks working in the mines and doubling production overnight.

The Doctor addresses the Dalek, promising to stop it whatever its plans. He is stunned to find out that Hensell will permit Lesterson to continue his experimentation on the Dalek. The Governor will not listen to the Doctor's arguments and so the Doctor decides that he must contact Earth just as soon as communications have been restored.

He starts to storm out, but stops before the Dalek. He decides to put its "servitude" to the test, ordering the creature to deactivate itself. After a long moment, it complies, it's eyestalk and sucker stick going limp. The Doctor leaves, unconvinced.

As soon as he is gone, the Dalek comes back to life. It had been a ruse all along. Lesterson is somewhat concerned, but accepts the Daleks argument that the order given was wrong. It cannot serve human beings if it is deactivated. Lesterson gave the Dalek power; his orders are the right ones. Hensell is somewhat concerned at the creature's power to reason but Lesterson dismisses his fears. All Lesterson sees is a tool to aid the colony, and he promises to learn all he can about what this Dalek is capable of.

Ben and Polly are still concerned about Deputy Governor Quinn and the outcome of the inquiry against him. They left abruptly and can no longer help him; it is clear that the Governor has already pegged him as guilty. In the meantime, the Doctor has already started working on a way to stop the Daleks. It is the most pressing concern. He races off for their quarters to try and create some weapon against them.

Back in Hensell's office, Quinn's inquiry reaches its conclusion. Bragen accuses him of being in league with the rebels, but Quinn refutes this. He didn't destroy the communications or attack the Examiner. In fact, he reveals that he is the one who sent for the Examiner. In order to put an end to the rebels before they became too strong to contain. Hensell is extremely angry to learn this, his trust in his deputy shattered. Bragen exploits this, telling the Governor that Quinn is only trying to stir up trouble to get Hensell removed. Then he himself can take over as Governor, blaming the whole thing on the rebels.

Quinn is stunned by the preposterous allegations, but misses the irony that it was Bragen himself who first blamed the Examiner's attack on the rebels. The Head of Security is a wily man and he convinces Hensell. The Governor has Quinn taken away to jail.

Hensell is devastated, not sure what to make of this seeming betrayal. He appoints Bragen acting Deputy Governor. Bragen accepts the new position silently, but his expression is one of quiet triumph.

In their quarters, Ben and Polly watch helplessly as the Doctor engages in a bit of vandalism. He has discovered a power unit that he needs to fight the Daleks and he smashes its casing to get to the interior circuitry, littering the floor with debris. Examining it, he finds it not quite complete for his needs and begins dismantling one of the bunks in the room, removing a metal bracket to affix to the power unit.

Ben and Polly look on, trying to ask questions. The Doctor says that they must work stealthily against the Dalek to avoid the wrath of Bragen and the Governor, who are convinced the Dalek will save the colony. Ben suggests kidnapping Lesterson to keep him from continuing his experimentation but the suggestion is greeted with no enthusiasm. The Doctor is sure they must act directly against the Dalek, showing his completed power unit to his friends. It might just be the answer to all their problems.

The three of them hurry off to the laboratory. They run into Quinn and his escort along the way. He tries to shout a warning to "the Examiner" about the rebels but he is dragged away by the guards. Polly is still concerned about his wrongful imprisonment but the Doctor refuses to listen. They must attack the Dalek problem first. A little injustice is better than wholesale slaughter.

Lesterson has continued his experiments with the Dalek, trying to ascertain the limits of the creature's intelligence. He and Janley have been feeding it questions on chemistry, which the Dalek answers rapidly and accurately. Lesterson becomes more and more excited with each correct answer.

The Doctor arrives, smiling broadly and speaking in a conciliatory manner. He wants to call a truce between them. Lesterson is sceptical at first but the Doctor's glib tongue convinces him. Not wanting to take any time away from his experiments, Lesterson agrees to the truce and invites "the Examiner" in to assist in the tests.

While the two men talk, Janley takes a phone call in a corner of the lab. Unseen by the others, she grabs a cloth-wrapped bundle and heads for the door. She tells Lesterson she's leaving but he barely spares her a glance.

Ben and Polly watch as the two scientists begin to test the Dalek's knowledge of physics. As the Dalek begins to explain the first law of thermodynamics, the Doctor slips away. Unseen by Lesterson, the Doctor makes his way to the main power source and connects his doctored power unit to it. The change in power affects the Dalek immediately. It screeches in pain and whirls uncontrollably.

Lesterson charges angrily at the power unit and disconnects it, shoving the Doctor away. The Dalek shortly returns to normal, announcing it has sustained no damage. The creature turns on the Doctor and approaches, a clicking sound emanating from the orifice where its gunstick normally resides. It is more than ready to destroy the Doctor for his interference. Luckily for him, the gunstick has been removed.

Janley heads to the Governor's office which is darkened and silent. There she meets Bragen. It quickly becomes apparent that they are working together to take over the colonists. But neither of them are really rebels. Bragen has used Janley to infiltrate the rebels (really a loose-knit small-scale group of malcontents), to stir them up in order to force Hensell from office. Then he can crush them, be hailed as a hero, and take over as Governor.

Janley has brought something to help him with his quest. It is the Dalek gun. She knows it is powerful - it killed Resno - and hopes it can be reactivated by the rebels. With it, Bragen hopes Janley can persuade them to go on the offensive and topple the Governor. Janley explains that she lied to Lesterson about Resno's death, convincing him that the man was only injured and "resting". She has dumped the body in the mercury swamp. His death will be leverage over Lesterson should they ever need to control the influential scientist.

Bragen is pleased with all of this and tells Janley to put that part of their plan in motion. However, the presence of "the Examiner" still bothers him. Quinn is out of the way, now he must do the same to the Examiner.

Having been expelled from Lesterson's laboratory, Polly and Ben search for the Doctor. There is no sign of him. Polly decides to leave Ben to search while she returns to their quarters. She is concerned for the mess that the Doctor left.

As Ben leaves, Polly is approached by Janley. Polly asks if she knows by chance where the Doctor is and Janley thinks quickly. She tells her that he has gone to the communications room to contact Earth. Janley directs her and then follows at a discreet distance.

Polly enters the communications room but finds it darkened and silent. Clearly there is no one here. As she turns to go, however, she is grabbed from behind by powerful hands. She struggles and tries to cry out but the man covers her mouth. Janley arrives and produces a sedative which she applies to Polly's mouth and nose through a handkerchief. Polly swoons to the floor. She is their prisoner.

The man is Valmar, one of the rebels. He is the man whom Janley believes can make the Dalek gun work. She shows him the weapon and he is confident he can do it. It is clearly a very powerful weapon. He thinks it could help them win "the revolution."

Ben has found the Doctor and the two of them have returned to their quarters. The Doctor lounges on a bunk, deep in thought and playing a tune on his recorder. Ben paces impatiently nearby, becoming angrier by the second. Finally, his anger bursts forth at the seemingly unconcerned Doctor. Polly is clearly missing. She said she was coming back here but no one has seen her in some time and the mess is still on the floor. The Doctor's only reply is to ask Ben what his next move would be if he were a Dalek.

Ben refuses to answer, trying desperately to generate some interest in the Doctor regarding Polly's whereabouts. Finally he is forced to drag the Doctor to his feet and haul him outside. They are going to search for Polly whether he likes it or not.

Back in the lab, Lesterson is now alone with the Dalek and the work continues. He explains to the Dalek that the Examiner will no longer bother them. He sounds a bit hysterical, but perhaps that is just from lack of sleep. Lesterson actually seems to be confiding in the creature, as if it is the only one who understands him. He tells the Dalek that "some people here" consider it an enemy, sounding almost parental. The Dalek assures him that it is a servant only.

As if to prove this, the Dalek indicates a nearby instrument and asks its function. Pleased at what he sees as the creature's curiosity, Lesterson says it is a warning system for meteorite storms, used to protect the colony's satellites. It is about 70% accurate. The Dalek says that it can create a system that is 100% accurate, given the right parts...and a power unit.

Lesterson is stunned at the possibility of a perfect system. His mind explores the possibilities and he is very excited. The Dalek repeats its need for the proper materials. Lesterson decides to ask the Governor for the materials immediately, sounding deliriously happy. His discovery and experimentation will undoubtedly save the colony. He hurries off.

As soon as he is gone, the Dalek heads for the power supply. Using its sucker stick, it increases the power, a surging hum in the background. It then heads into its capsule, where its compatriots await.

The Doctor's heart (and mind) are clearly not on the task at hand. Ben must finally say something. The Doctor is talking to himself, muttering about "power". He is still thinking of the Daleks' next move, continuing his single-minded thought process. There is a notice board nearby and the Doctor takes down one of the papers tacked there, using it to do some mathematical calculations.

But he has incomplete data and cannot get to the answer he seeks. He's very frustrated. However, he brightens again when he sees Lesterson go past down another corridor, away from his lab. That means they can get in and look around some more. The Doctor excitedly hurries off. Ben reluctantly follows.

They notice some changes in the lab since last they were there. The hum of power is stronger and now several cables lead from the power unit into the Dalek capsule. As they move toward the capsule, the Dalek appears, blocking their way. It is belligerent, far from the "servant" it pretends to be, and the Doctor presses his challenge.

He sends Ben to disrupt the power on the generator, which causes an almost pained reaction from the Dalek. While it is distracted, the Doctor tries to get into the capsule. However, he is greeted by two more Daleks - both active, both armed.

Fearing for their lives, the Doctor instructs Ben to run on his command. They just manage to escape.

The unarmed Dalek, leader of the group, has recovered from the "attack" and informs its comrades that it has sent Lesterson for needed materials. Soon they will have them, along with a power generator that they can use to create static electricity. Then they will conquer. Conquer! Conquer!!

The Doctor and Ben have sought out Lesterson in Governor Hensell's office. The Doctor tells of the two new active Daleks and their armaments. The Daleks have revived themselves and he is certain they are intent on destruction. Amazingly, Hensell will not listen. Lesterson will simply turn off the power for a moment and disarm the new Daleks. Then all three can be put to use to benefit the colony.

With dreams of wealth and prosperity - and perhaps to spite the high-handed "Examiner" - Hensell gives Lesterson carte blanche with the Daleks. The Doctor is furious at this wilful blindness.

With that done, the Governor is ready to leave on a tour of the perimeter of the colony. Bragen is in charge and is instructed that Lesterson is to receive everything he needs...including a guard on the lab to keep the Doctor out. Furiously, the Doctor and Ben follow him out. Bragen calmly assures Lesterson that he can "keep the Examiner quiet" while he gets on with his work, but the implied threat is lost on the single-minded scientist.

The Doctor and Ben return to their quarters, the Doctor angrily denouncing the greed and ambition which is driving Hensell's decisions and blinding him to the escalating threat of the Daleks. If only he know the cost his actions will have. Ben, however, is more worried about Polly and addresses the issue when Bragen appears unexpectedly at their door. The Doctor plays his recorder, pointedly ignoring the Deputy Governor.

But Bragen has come to see the Doctor... for a very specific reason. He announces that a man's body has been found in the mercury swamp - the real Examiner. The Doctor is an impostor and he hopes to use that knowledge to keep him under control. However, Ben and the Doctor know that only the Examiner's killer could know this and Bragen's ruse is defeated.

However, neither Bragen nor the Doctor can act on their respective knowledge with out revealing themselves. Stalemate. Bragen leaves with a warning: leave Lesterson and the Daleks alone. Now the Doctor has two enemies to fight, although the Daleks are his main concern.

Suddenly an envelope is shoved under the door. Ben opens the door but sees no one. He opens the letter and reads it aloud. "The girl is safe. She will remain so as long as you leave the Daleks alone." Polly has been kidnapped!

In the laboratory, Lesterson receives confirmation of the Daleks' servitude. They have voluntarily removed their gunsticks at his request. The Examiner was clearly wrong about them and he is pleased. He doesn't even seem to worry about how the other two Daleks came back to life without him.

The Daleks are insistent about receiving their requested material, especially the power plant. Lesterson tells the lead Dalek that it will have everything it wants.

The lead Dalek confers with its comrades, relating the news. Suddenly the entire group begins triumphantly chanting "We will get our power" over and over and over.

Lesterson becomes more and more alarmed as the Dalek "power" chant continues. Unseen, he moves to the power control and turns it down. The Daleks' movements slow down and their voices slur. The lead Dalek orders the power supply restored. Lesterson addresses the creatures, some fear in his voice. He is trying to regain mastery over the Daleks, to make them remember that they are servants.

He tells them at all the power they need must come from the one generator and that he controls it. His confidence returns fully when the Daleks agree to obey him and he restores full power to them. Two of the Daleks return to the capsule, supposedly to "await his orders". Lesterson believes this, despite the proven deviousness of the creatures, and turns his attention to the blueprints for the new meteor storm computer.

He is amazed at the intricacy and efficiency of the design. It will be a great improvement. Lesterson is pleased at the cooperation the Dalek has given, but he does not note the new edge of menace in the Dalek's demeanour. Clearly the creatures are only playing him along and continuing with their own agenda.

Bragen has now fully ensconced himself as the Deputy Governor - uniform and all. He sits behind the Governor's desk as Valmar works to complete repair of the telecommunications system. There has been a severe interruption colony-wide and the work is slow. Bragen is very cross at the time it is taking. Valmar completes the initial connection but still must finish the longer-distance circuits. But Bragen - feeling his new power - is unsatisfied and picks a fight with Valmar. He promises he will "be watching" Valmar in the future and dismisses him.

The Doctor and Ben burst in to report Polly's kidnapping. Bragen seems less than concerned for her safety and Ben for one is not convinced he will do anything at all to help.

They are interrupted by the arrival of a Dalek. It is acting as a servant, bearing drinks. The Doctor finds this very disturbing but Bragen seems pleased to have the creature working for him. Ben gets angry at Bragen's detachment and decides to start a search for Polly himself.

The Doctor has his mind on other things, though, as he watches the Dalek leave. He wonders how much longer the Daleks will be able to move about on the colony's floors. They are not metal, which the Daleks need for free movement. Ben grabs him and pulls him out of the office to start their search, uninterested in the Daleks or their movement on metal.

Suddenly the communications system rings. On the monitor is Governor Hensell, still touring the perimeter. He is testy, having been prevented from calling in by the communications blackout. Bragen assures him that all is well and that the Examiner is being well taken care of. Bragen is pleased to learn that Hensell will not be returning for at least a day, perhaps two.

Bragen rings off and is startled to see that the Dalek has silently returned. How long has it been standing there? It asks if Bragen has finished his drink, which he clearly has not. The Dalek rolls away, Bragen watching after it with concern.

As the Doctor and Ben head away from the Governor's office, the Doctor is still trying to explain the Daleks' dependence on static electricity and metal flooring. They notice some commotion at the message board. Janley has just posted an item and a man, called Kebble, seems absorbed in it.

Ben is just about to comment on this when three Daleks glide by. The Doctor protests at the madness of letting these evil creatures have free run of the colony, but Ben points out a much more disturbing problem: the number of Daleks. There was one serving Bragen, and now these three. That makes four! Where did the fourth one come from?

The Doctor immediately fears that Lesterson must have found more in the capsule. They must go to the lab. Perhaps they can question Lesterson and Janley about Polly as well.

Before they go, they notice that Kebble has left the message board rather hurriedly. They find it strange but can see nothing unusual in the message posted. They head off as another man approaches. Just before the Doctor turns the corner, he notices the man copying something off the board. The man starts when he realises he is being watched and hurries away. Very odd indeed.

Janley makes her way to the lab to find an agitated Lesterson waving a list at her - the Daleks' latest material request. It seems excessive to him and he cannot fathom how they could have used up all that was given to them just hours before. Janley thinks nothing of it, though, assuming the creatures are simply building more things for the colony.

But Lesterson cannot stop worrying. He is willing to give the Daleks latitude so long as he can control them, but he is beginning to fear their autonomy and original thinking. He believes the Examiner may be right - the Daleks may need to be destroyed.

Janley is concerned about this line of thought. The rebels have need of the Daleks... intact and functional. She decides she must play her trump card to stop Lesterson - Resno. She informs Lesterson of Resno's death, the illegal disposal of the body, and the unauthorized experiment that killed him. And she blames it all on Lesterson and his carelessness. She tells him that he murdered Resno and she will tell the Examiner if he tries to stop the Daleks.

Lesterson is devastated, realizing that he has been blinded by his scientific single-mindedness - blinded to the extent of Janley's callousness and her involvement in the rebellion. She is clearly ruthless and she has now turned on him to aid her cause. Something inside him snaps; his "benevolent" experimentations are now beginning to spiral out of his control in more ways than one.

The Doctor and Ben burst in, inquiring about Polly. Lesterson tries to brush them off, his mind whirling with the implications of Janley's words. He has begun to sweat. The Doctor turns his attention to the Daleks, asking if Lesterson has been building more of the creatures. He says, honestly that he hasn't, and the Doctor surmises they must be duplicating themselves. The enormity of this possibility terrifies Lesterson. He picks up the Daleks' material list and a horrifying realisation dawns. The Doctor speaks with Janley, saying that nothing is beyond the Daleks, given the right materials.

Lesterson nerve breaks and he cries out, crushing the materials list and sinking onto a lab stool. He has given the Daleks all they need and they are completely out of control. All that the Examiner prophesied will come true...and it is all his fault! These thoughts echo in Lesterson's head but he can say nothing at all. He buries his face in his hands, rocking back and forth and crying out. He is a broken man.

Janley reacts quickly, blaming his state on overwork and badgering by "the Examiner". She summons the guards and forced Ben and the Doctor out. Once alone, Janley ignores Lesterson completely and goes to the phone. She calls Valmar and orders him to come to the lab immediately. Then she leads a babbling Lesterson to a couch to rest. She gives him a glass of water, laced with a sedative.

Valmar arrives and is concerned over Lesterson's state, but Janley plays it off as overwork. While he is out, Valmar is to lay in the new power cable the Daleks have asked for. She is clearly on top of everything, taking great advantage of her power over Lesterson. As Valmar gets started, Janley calls into the capsule to tell the Daleks. They are pleased, but their pretense of servitude seems to be lapsing.

Valmar is somewhat concerned but bows to Janley's will. She is certain the Daleks will help them - the rebels - in exchange for this assistance. He gets back to work after he acknowledges that he saw the notice Janley posted on the message board.

The Doctor has renewed his interest in the message board as well. He is intensively studying the notice which absorbed the two men earlier. In an innocuous posting, he has detected a message in code that calls a rebel meeting tonight, 2000 hours, in rocket room P. He decides that they should attend, only showing up early to hide themselves. Ben hopes this will help them discover what's happened to Polly.

Later that night, Ben and the Doctor wait in hiding in rocket room P. They have been here for some time and Ben is getting antsy. Before long, though, the rebels begin filtering in. Men and women enter and convene, but one man stays deep in the shadows, saying nothing but watching intently. Also joining them, a Dalek.

Janley has called the meeting to demonstrate the Dalek and its weapon. Valmar has brings the modified Dalek gun forward and starts to reconnect it to the Dalek. It has an extra attachment to it now - a control device designed to regulate the fire power. Janley receives permission from the shadowy man to commence a demonstration. He is clearly the leader of the rebels but Ben and the Doctor cannot see him clearly from their hiding place.

The demonstration begins and the Dalek fires at a piece of two inch thick tungsten steel. The powerful energy beam punches right through the metal. The rebels murmur in shock and awe and Janley must silence them. Several of the rebels are very frightened at the creature's power. The people have been told very little about the creatures until now and it is somewhat overwhelming. Kebble speaks for them all when he says he doesn't trust that Valmar can control it. He is certain it will turn on them or perhaps not know the difference between rebels and the Governor's guards. He wants proof of Valmar's assertion that he can control the Dalek.

Janley volunteers to be a target, to test Valmar's control. The murmuring ceases and everyone realises she is serious. The man in the shadows agrees and the Dalek turns toward Janley. There is a long tense silence before the Dalek fires. But Valmar has deactivated his control switch and no energy beam is released. There is a collective exhale from the group.

Janley has had enough of this foolishness and orders Valmar to disarm the Dalek. She has proven that they can control the killing power of the Dalek and she has cemented her own power within the rebel group. She turns her attention now to Polly. Kebble assures her she is safely locked up. Ben hears all this and reacts quickly, rising from hiding to confront Polly's kidnappers. But he is hopelessly outnumbered and is quickly knocked unconscious.

Janley fears that the commotion has been heard and she hurriedly breaks up the meeting. Ben is taken away to be locked up. The Dalek, however, is left behind in the rush. So is the leader of the rebels, the man in the shadows. The man has stayed behind deliberately. He has no fear of the Daleks, the guards, or of discovery. And he knows that the Doctor is here, still hiding. He calls for him to come out. It is Bragen. He is leader of the rebels!

As the Doctor emerges, the Dalek turns on him. Valmar was unable to complete the removal of the creature's gunstick. It is still armed and intent on killing its mortal enemy, the Doctor. The Doctor taunts Bragen to prove his control over the Dalek by stopping it from killing him. Bragen does so, but barely. The Dalek hesitates for a long moment before turning away. On Bragen's orders, it leaves the room to fetch a guard.

The Doctor threatens to expose Bragen to the Governor, but Bragen is already ahead of him. He has arranged for the body of the real Examiner to be "discovered" in the swamp and for the Doctor to be exposed as a fraud as soon as the Governor returns. The Dalek arrives with guards who lead the Doctor away.

Janley also returns, glad to see "the Examiner" out of the way. All that leaves between them and the leadership of the colony is the Governor. Bragen promises to deal with him, as well as the Doctor and Quinn, in due course.

Ex-Deputy Governor Quinn is surprised to see "the Examiner" being placed into an adjacent cell. Quinn is angry and blames the Doctor for his incarceration. The Doctor examines the lock on the cell as they converse. It is activated by a sound box carried by the guard, emitting a specific frequency. Quinn is shocked to learn that Bragen is the leader of the rebels and is more determined than ever to escape and stop him.

But there are more surprises for Quinn. The Doctor admits that he is not the real Examiner and that Bragen murdered him. Quinn knows that they must try to get help from Governor Hensell. As poor a leader as he is, many of the people support him. He is the only one who can help them... if only they can get free and contact him.

Back in the laboratory, Lesterson comes to, unseen by the Daleks who swarm about the room. He watches cautiously as one Dalek orders another to take up a position and guard the communications room. Lesterson realises that the Doctor was right all along - the Daleks are completely evil and conspiring against the colony. His mind slips further.

Shortly the lead Dalek returns to the capsule and Lesterson is alone in the lab. Despite the fear gnawing at his mind, Lesterson finds himself moving in to the capsule. It is as if part of him still cannot believe what he has learned. He wants more proof.

Inside, he hears the sounds of activity and moves toward it. There are several Daleks moving about, indicating that somehow the creatures are duplicating themselves. Soon he discovers how. Through an observation window, Lesterson sees a conveyor belt on which the bottom halves of several Dalek casings move. Each one is filled with a bubbling organic mass and then the top added. He watches the process over and over in horrified fascination.

Each new Dalek comes off the assembly line pledging itself as an enemy of all human beings. The Daleks are all armed, they are all independent, they are all completely hostile.

Lesterson's rational mind shuts down in the face of this enormous horror. Dalek after Dalek rolls off the assembly line, all ready and able to destroy the colony. Panicked, Lesterson rushes from the capsule and back into the lab. He is desperate to stop the Daleks but is unable to think straight. He closes and locks the main capsule door but that is all. He is certain it will not stop them for long.

Janley enters and is alarmed at the mad look on his face. He babbles to her about the Daleks duplicating and how he started it all, but he is sobbing and nearly incoherent. He moves frantically, looking for some way to stop them and dodging Janley's attempts to subdue him. He seizes on the power supply, realising he can still has the ability to stop the evil creatures - by eliminating their power.

He vows to melt the Daleks down with laser torches and Janley becomes alarmed. The rebellion will be jeopardized without the Daleks and she threatens to reveal Resno's death to try and stop him. But Lesterson is far beyond such threats. He will be responsible for the death of everyone on Vulcan if he doesn't act. He is clearly out of his mind and beyond manipulation. He even taunts her to reveal what has happened. Janley, knowing she has lost control over him, races from the laboratory.

Lesterson manages to pull himself together to phone "the Examiner" for help but is cut off... by a Dalek! It has used a secret exit from the capsule and announces to him that they have the capacity to store power and will soon have their own power source. Lesterson no longer has any control over the Daleks. Horrified, he races from the room, desperate for some means to stop the evil creatures.

The Daleks return to their planning, unconcerned over this minor incident. However, they still need to appear benevolent to the colonists. They are still unarmed and the lead Dalek orders that no more than three Daleks should be seen together around the colony. They must keep their numbers secret until they are ready to "teach these humans the law of the Daleks."

Lesterson races through the corridors and literally runs into a guard. He stops only long enough to learns that the Doctor is in prison. He is confused for a second but then races off toward the prison without another word. The guard, concerned at the scientist's mad glint and agitated manner, decides to follow him.

Janley returns to the laboratory with Kebble and a bound and gagged Polly. She is glad to see that Lesterson is not here but seems to think nothing of what might have happened to him. She tells the lead Dalek that Polly is an enemy but the creature seems unconcerned.

Polly is ungagged and immediately confronts Janley, labelling her and the other rebels as fools for trusting the Daleks. She's learned from the Doctor that the Daleks are only pretending to be subservient while it suits them. They will not remain so once the rebellion begins. Janley has enough of this and forces Polly into the Dalek capsule for safekeeping. Kebble is to stay with her.

Janley tells the Dalek that Valmar will soon arrive to install the final requested power cable. She is completing a task that Lesterson did not and its installation is known only to them. The creature is impatient to have it. It explains that the new cable will complete the power circuit to convert the colony's power to usable static electricity. Janley is impressed at this, but doesn't really grasp the implication of full mobility for the Daleks. She assures the Dalek that work will be completed soon now that there is no one to interfere with their plans.

In the cell block, the Doctor chats with Quinn, speculating on how the Daleks have managed to convert the colony's power into static, all the while trying to trip the lock on his cell using varying levels of water in a glass. Running his finger over the rim of the glass produces tones that he hopes will open the door. All he is succeeding in doing is annoying Quinn. He is also now out of water, having added and subtracted so much that his pitcher is empty. He must get more.

Suddenly a commotion breaks out as Lesterson forces his way past the guards, desperately trying to speak to the Doctor. He struggles against the guards to try and tell him that the Daleks are reproducing themselves and have their own power. He is sobbing and ranting but his desperation is clear. The guards finally subdue and drag him off to Bragen. Through this the Doctor has said nothing. As Lesterson is led away, the Doctor finally speaks - to ask for more water.

Quinn is horrified at the news Lesterson has imparted and is disgusted by the Doctor's apparent disregard. He sounds off and then retreats into his cell.

The Doctor is pleased when the guard returns with water very quickly. As the guard opens and closes the door, the Doctor listens carefully to the tone emitted. The guard leaves and soon he is working on replicating the resonant tone with the water in the glass. As he works, Quinn becomes more interested. He realises that the Doctor wasn't ignoring Lesterson but concentrating on doing something more pressing. He apologises for his outburst and urges the Doctor to continue.

Lesterson is brought before Bragen but will not answer any questions. He starts in fear when he sees a Dalek at work in the office, laying a power cable. The creature lies and says it is for the colony's emergency power supply and that it was Lesterson's order. He protests but due to the reports of erratic behaviour he's heard, Bragen does not believe him. He sends the Dalek away and addresses the dishevelled, wild-eyed Lesterson.

Lesterson demands to speak to the Governor, desperation in his voice. He says the Examiner was right about the Daleks and they are all in terrible danger. He is interrupted by Janley, who immediately begins patronising Lesterson and accusing him of forgetting things. Lesterson only becomes more agitated, crying and trying to warn Bragen that Janley is in league with the Daleks. Little does he know that Bragen knows this all very well. Janley and Bragen keep up the pretense, just in case Lesterson's not entirely mad. Bragen has the guards take him away and placed under restraint. Lesterson is despondent - no one will listen to him.

Inside the Dalek capsule, Polly watches as Valmar works at attaching power cables to a junction box. A Dalek watches over them both. Valmar seems annoyed at the work being placed on him, especially when Kebble arrives with more cables to be added to the load. He says it can't be done without a new box.

The Dalek goes away for the moment and Polly immediately starts to talk, immediately igniting a row with the surly Kebble. She learns from him that Ben is all right but is being held captive as he recovers from his beating. She also learns that Valmar is uncomfortable with the violence that seems to be escalating around their rebellion, in opposition to Kebble.

Polly tires to exploit this difference, explaining the folly of depending on the Daleks to fight the Governor. She assures both men that the Daleks are xenophobic and will turn on them all before long. Valmar seems to take this to heart, noting Resno's death and the fire power demonstration they saw. If the Daleks do turn, they will be unstoppable.

Polly tries to press this point, explaining that the Doctor is not the real Examiner but that he has special knowledge about the Daleks - vital information on their evil methods. It seems that she may be getting to Valmar but is forced to break off when the Dalek returns to check progress. Valmar says he needs another junction box to complete the work and the Dalek leaves to check on this.

Polly tries again, but Valmar is somewhat resistant, bowing to the Daleks' clear technological superiority. But Polly turns this around, saying that their superiority is why they hate everyone and wish to exterminate them all. This seems to work until Polly links the Daleks with Janley and says that Janley cares more about the Daleks than her rebel friends. Valmar falls silent and gets back to work.

The Dalek reappears, announcing the arrival of the new junction box outside and Valmar barely responds. A smug Kebble explains to Polly that Valmar is "soft on Janley". She has miscalculated her cleverness. Valmar is sullen and will listen to no one.

Meanwhile, Governor Hensell has returned from his tour of the perimeter to find much changed in the colony. A Dalek is laying cable in a corridor and the guard there doesn't even recognise him. What's more, the guard has been brought in from the interior and is armed. He says he is a squad leader in "Bragen's guard". Hensell takes this in with growing concern. He heads for his office to question Bragen.

The Doctor's experiments with the water have been unsuccessful. But he has managed to annoy the guard. Feeling this may work better, the Doctor adds his recorder to the mix and soon the guard opens the cell door, intending to confiscate all noise making devices.

As soon as he is inside, the Doctor tosses water in his face. He staggers back into the wall adjoining Quinn's cell. Quinn grabs the guard and knocks him out. The Doctor takes the locking device and uses it to free Quinn. Removing the water and glass (so that the guard won't be able to escape that way), the Doctor locks the cell and he and Quinn are off.

The Governor returns to his office to find Bragen engrossed in signing papers, barely acknowledging the Governor's presence. The affront is clear and Hensell becomes testy, forcing Bragen to look up from his work. He is concerned about the Examiner and what trouble he may have gotten in to and he wants answers. He is surprised to find out that the Doctor is in jail. Bragen explains that the Doctor is an impostor, jailed on suspicion of murdering the real Examiner. Hensell finds this hard to believe and the actions precipitous. Bragen clearly doesn't care what he thinks.

Hensell becomes livid at the clear disrespect shown by Bragen and he orders the guards to remove him from the office. They do not respond and Bragen announces that he himself is now Governor and the guards obey only him. Hensell realises suddenly that Quinn's mistrust of Bragen was well-founded all along and vows to stop him. However, he cannot even leave the office due to the guards blocking the way. However, Bragen dismisses the guards and places Hensell behind his desk before summoning his Dalek servant.

Bragen wishes to keep Hensell around for the time being, as a puppet. Hensell of course rejects this, becoming indignant. Bragen is left with little alternative. He produces a Dalek gunstick and chats calmly as he attaches it to the waiting Dalek. Hensell has not seen this weapon before, but the menace in Bragen's voice and the eagerness of the armed Dalek is perfectly clear to him. He refuses to be intimidated and give up his people to rule by a mad despot.

Without hesitation, Bragen orders the Dalek to fire. Hensell slumps to the floor, dead.

The Dalek is interested in the reasons why humans would kill other humans but Bragen angrily dismisses the creature. It obeys and moves off, but not before its gunstick is removed. Bragen takes the Daleks' obedience as the first step toward his rule over the entire colony. His words and manner are truly ruthless. Governor Bragen.

The Doctor and Quinn make their way to Lesterson's lab. However, they are forced to hide when a Dalek emerges from the capsule, along with Valmar. He has completed installation of the power cables. The Dalek is pleased but maintains the façade of servitude, saying the independent power will allow the Daleks to be "twice as... useful" to the colony!

Janley rushes in to inform Valmar of the Governor's return. They must act quickly, leaving Kebble to watch over Polly. The Dalek offers to go with them... just in case. Janley reluctantly agrees.

The Doctor and Quinn emerge from hiding and head for the capsule. The Doctor is concerned that they have very little time to stop the Daleks before they are fully independent and can begin the destruction of the humans.

Inside the capsule, Kebble hears talking outside and moves to leap on the Doctor. However, Polly sees what is happening and shouts a warning. There is a struggle and Kebble is knocked unconscious. The Doctor rescues Polly.

Polly tries to tell the Doctor all that she's learned, but he has already discovered it all. She is nervous and frightened. Suddenly there is a commotion at the capsule as an armed Dalek emerges. The entire group is in danger. The Doctor manages to get Polly and Quinn out the door, but he hesitates, trying to find some way to barricade the Daleks inside the lab. He barely escapes, jamming a tool into the door handles outside. The humans have escaped.

One of the Daleks returns to the capsule while the other uses its weapon on the door. Outside, the tool melts and dislodges. The Dalek glides out after the fugitives.

Inside the capsule, the mass of Daleks has gathered. The time is nearing for them to take action. They have gathered information and now know that rebellion among the humans is imminent. As soon as they are fighting among themselves, the Daleks will emerge in force and exterminate. An endless chant of "Exterminate!" rises from the group, full of menace.

The Doctor, Polly, and Quinn have gone to the Governor's office. They are saddened to find Hensell's body, killed by a Dalek weapon. Quinn is despondent, certain that their only hope of uniting the colony to fight the Daleks is now dashed. Quinn realises that it is up to him.

Bragen enters suddenly, with armed guards. He tells the group that the Daleks killed Hensell for opposing them and that he is now Governor. Very matter-of-factly, he declares martial law and has all of them arrested. Bragen believes the Daleks will obey his orders and support him, but the Doctor assures him that is not the case.

In the capsule, the Daleks continue their chant, voices rising. Suddenly the chant breaks off as a Dalek rolls forward with new orders. The rebellion has begun and the Daleks are free to exterminate all humans.

The Daleks pour out of the laboratory to take up positions, ready to exterminate all human begins.

The Doctor, Polly, and Quinn are being herded along by two guards. The Doctor is alarmed when he sees an armed Dalek apparently standing guard in the corridor. It stops them from moving forward, saying the area is restricted. Quinn becomes indignant and a second Dalek arrives to reinforce the order. They will move away or they will be exterminated.

The Doctor recognises this behaviour immediately. The Daleks are no longer making a pretense of obedience. The guards realise there is something wrong as well and urge their prisoners to move on.

In the Governor's office, Janley is elated. The rebellion is effectively over and Bragen is in control, just as they had always planned. And very little blood was shed. However, it is not over as far as Bragen is concerned. If Valmar, Kebble, and the others can rebel against Hensell, they can do the same against him. He wants them killed and plans to use the guards to do so.

Janley is horrified at this callousness and hesitates to commit to the plan. He produces a gun from his desk and points it at her, forcing her to agree. Unknown to both of them, Valmar has overheard the entire plan. He has not however seen the gun and believes that his beloved Janley has knowingly sold out the rebels.

The guards are nervous as they traverse the corridor. They cross a t-junction and are intercepted by a Dalek. Thinking quickly, the Doctor sees a chance to escape. At a shouted command, Quinn goes into action and knocks out one of the guards, the second is blocked by the Dalek and Polly, Quinn, and the Doctor are able to escape down the corridor.

Fearing for his life, Valmar has freed Ben from confinement and has brought him back to the Examiner's quarters. He explains Bragen's plans to Ben, but gets little sympathy. Valmar believes that only the Doctor can help them now and plans to find him and bring him here. Ben is to wait for him to return. With no other options, Ben reluctantly stays behind.

In his office, Bragen receives work that the rebels are beginning to gather. They are as yet unaware that he has taken over. He orders the guards to be ready to attack them quickly before their groups get too large. Then he addresses the whole of the colony, announcing that Hensell has been murdered - by the rebels! He assures the people that he is in control and will deal with the murderers swiftly.

In his quarters, Ben hears the message. He knows that chaos will break out very soon. Just as the message ends, the Doctor, Polly, and Quinn enter. They have come on their own, never having been contacted by Valmar. Ben explains that Bragen has lied to give the guards an excuse to attack the rebels. Once the rebels begin fighting back, the guards will have a legitimate reason to crush them.

The Doctor cares little for all of this, knowing that the Daleks will take advantage of the chaos to kill everyone - rebel or guard or bystander. That is his only concern and he heads off on his own to try and stop the bloodshed. Quinn is to watch over Ben and Polly. Both the young people are put out at being left behind.

The Daleks at last are in position and the orders are given to commence extermination. The human beings will now learn who are the true masters of this planet.

The Doctor runs into Kebble, who is being pursued by guards. The guards try to arrest them both, but the Doctor's worst fear comes true. A Dalek opens fire on them all, caring naught for whom it hits. The guards fire their guns but they are useless. The guards are killed, but the Doctor drops to the floor with Kebble. They avoid the Dalek fire and manage to escape.

Janley arrives at Lesterson's laboratory, looking desperate. She is surprised to find Valmar there, and even more surprised to hear the venom in his voice. He explains that he overheard her conversation with Bragen and he is looking for some way to stop the guards from killing all the rebels. Janley has come here for the same reason. She tells him that Bragen forced her to agree. She realises that he is a power-mad fool who underestimates both the rebels and the Daleks. He must be stopped.

Daleks appear from the capsule, having overheard their conversation. They offer to fight for Janley and Valmar if they will conduct the Daleks to the centre of the rebel group. Janley and Valmar agonise over this, even though it is what they both had in mind. The Daleks have lied to them all right along, but Janley agrees as she feels there is no other way to stop Bragen and the guards. Valmar goes along with his beloved Janley. The humans lead the Daleks out.

The Doctor bursts into his quarters, his face a mask of panic. He is lucky to have reached here in one piece due to the marauding Daleks. And they are close on his tail. The only way out is through the window. Ben and Quinn force it open and the group starts to crawl through. Kebble bursts into the room just as the Doctor starts to leave through the window. He too is trying to escape, but the Daleks are too close. He is killed by a burst of Dalek fire and crumples to the floor. The Dalek approaches the window, still firing, but the Doctor has already escaped.

Governor Bragen issues another order, one that may inadvertently save many people. All loyal citizens should stay indoors while the guards help crush the rebels. If only it were as simple as that. A guard bursts in, panic-stricken, announcing that the Daleks are attacking the guards. Bragen is shocked by this news and orders the guards to fight back, despite the uselessness of their guns. He will not listen to the guard's panicked protestations and orders him out. He must have time to think!

At a rebel stronghold, Janley and Valmar prepare to fight the guards. One Dalek is with them and they hold the control device for its gun. While some of the rebels shoot it out with the guards, Janley sends the creature to attack the guards. It does so successfully, but then it continues to fire as it turns back. The rebels' barricade is destroyed and several rebels are killed. Janley and Valmar are horrified as they realise they can no longer control the Dalek - as if they ever could.

The Dalek announces that the rebels' usefulness is over and turns on Janley and Valmar. They are saved by the timely arrival of another guard, who distracts the Dalek by shooting at it. He is killed instantly and Janley grabs Valmar to make a run for it.

The Doctor, Ben, and Polly reach Lesterson's laboratory. The Doctor is desperate to find some way to stop the Daleks and he thinks this is the best place to start. Besides, there are less Daleks here than in the corridors. Also in the lab is Lesterson; somehow he has escaped confinement and returned to "the scene of the crime". His mind is gone and he speaks like a child, his eyes wide. The Doctor and his friends are forced to join him in hiding when a Dalek glides from the capsule. It quickly leaves the laboratory and the group is free to talk.

The Doctor tries to find out from Lesterson how the Daleks are getting their power but the shell-shocked scientist will not tell him. He tells the Doctor how much he "admires" the Daleks and their superiority; he is convinced they are here to destroy mankind and "take over" where homo sapiens has failed.

More Daleks arrive and the group sinks back, silent. They confirm that their static circuit is nearly complete and that the humans are being systematically exterminated. From outside, sounds of firing and human screams issue. All their plans will soon be complete. The Daleks continue about their work.

The Doctor becomes very alarmed, realising that he is nearly out of options to stop the Daleks. Their power can no longer be turned off to any effect. He must think of something else, a task made no easier by Lesterson's insane assertions that they are all finished and the "marvellous" Daleks will soon take over.

Janley and Valmar race through the corridors, trying to elude the Daleks, their desperation growing with every turn. They run into Quinn, also traversing the corridors, and join forces to try and escape the Dalek cordon. But they are unable to do so. The Daleks are everywhere. The humans run into a Dalek and Janley is mercilessly gunned down.

The sounds of murder fill the laboratory as well, making Polly scared and angry. Ben, distressed by Polly's reaction, turns on Lesterson and blaming him for what has happened. Lesterson returns to lucidity one last time, explaining that Janley and Valmar took his initial controlled power experiments and secretly made them independent. They gave the Daleks their own power and Valmar rigged up the secret cable right from the colony's main power supply. The Doctor knows what he must do: he must find Valmar in order to disrupt the Daleks' power before it is too late.

As the sounds of Dalek gunfire increase outside, Lesterson descends fully into madness. The Doctor forces his companions to stay put here while he goes on his own to find Valmar.

The Daleks have moved on and Valmar has returned to find Janley. There are tears in his eyes as he realises that she is dead. Quinn tries to get him to move on, knowing it is not safe here but a devastated Valmar can't make himself go. He knows what everyone thinks of her now, but he knows that she was only trying to help the colony. He weeps as much for her tarnished memory as for the loss of her life.

The Doctor finds the men and immediately starts asking Valmar questions. There is no time to answer, however, as Quinn spots a Dalek approaching. The three of them drop to the floor and play dead. Among all the other bodies littering the corridor, they look like just three more corpses. The Dalek scans the dead for any sign of movement as it passes but finds nothing. It moves on, mopping up.

Valmar is blank faced, as if he cannot even understand the Doctor's questions about the power supply. Quinn finally forces him to answer: the main cable is inside the Dalek capsule but there's no way of cutting it off. The Doctor has other ideas but does not stop to explain. He needs a diversion and the only thing for it is the guards. Quinn must go to Bragen and convince him to use his guards to try and hold off the Daleks for a little while longer. It is the only way.

But Bragen has a lot on his mind right at the moment. None of his guard units are responding to his increasingly frantic calls. He thinks it's a matter of insubordination, but it is a matter of extermination. Thinking the creatures are working for the rebels, he addresses a message to the Daleks audible throughout the colony. He begs the Daleks to work for him, the Governor, and not the rebels. He promises them anything they want, not realising that they already have all that they need. His voice becomes more insistent as he speaks.

Ben hears the message and dismisses Bragen as nuts. Thinking practically, he decides that he and Polly need some place safe to hide while they wait for the Doctor. A nearby storage cupboard does the trick nicely.

Quinn enters Bragen's office just as he finishes his message. His calm demeanour unnerves Bragen, as do his words. He is also holding a gun. The Daleks are working on their own now, mowing down guards and rebels alike. They obey no one. But Quinn knows that there are still a considerable number of guards in the interior of the colony; they must be ordered here immediately even though they will undoubtedly become fresh targets for the Daleks. At least the distraction will give the Doctor some time to deal with the Daleks. Bragen initially refuses to sacrifice his guards, somehow thinking that there might be some way out for him when this is all over, but Quinn's insistence that there will be nothing left of the colony if the Daleks are left unchecked finally wins him over. Bragen calls in the guards. They can only hope that it works.

The Doctor and Valmar reach the laboratory and are reunited with Ben and Polly. They report that a number of Daleks went out just now in reaction to Bragen's message. Hopefully they will be engaged with the incoming guards for long enough. The Doctor braces himself and heads into the capsule. He only hopes there are no more Daleks inside. He manages to bring out one of the junction boxes and rearrange some of the cables attached to it, but they are all forced to hide when two Daleks arrive.

One Dalek reports that static power is now being stored; they have no more need for the colony's power system and it can be disconnected. But they notice the cables have been moved and become concerned. The Daleks begin to search the room, nearly finding the Doctor and his friends, but Lesterson bursts from hiding in the cupboard to distract them. He tells the Daleks - in an all-too-familiar monotone - that he is their servant and will tell them who moved the cables. But they do not need humans any more and they kill him, turning so casually on the man who gave them new life.

But the distraction is all that the Doctor needed to reach the main power generator unseen. He finishes his connections while the Daleks return to scanning the room. They find Ben and Polly and fire, but Ben and Polly dodge the blasts. The Doctor presses home the final switch and the Daleks suddenly cry out in agony, losing control of their motion and spinning helplessly. Smoke begins billowing from their casings as their cries continue.

All through the colony, the same thing happens. The creatures cry and spin helplessly, losing control of all functions. Before long their voices and their movements run down like clockwork toys. The Daleks have been destroyed.

In the Governor's office, Bragen and Quinn examine a dead, smoking Dalek. Neither of them know how it happened, but both know that the Doctor is behind it. Bragen takes advantage of the distraction to attack Quinn and disarm him. They wrestle for the gun but Bragen is the victory; Quinn is at his mercy. Bragen still intends to restore law and order to Vulcan - his law. Quinn taunts him, knowing that his attempt to remain in charge is futile, and Bragen raises his gun.

A shot rings out, but it is not from Bragen. Valmar has entered unseen, killing Bragen. Valmar is disgusted at the killing he has witnessed and he throws away his gun. Quinn is more practical, his mind already going to all the repairs that will be needed in the colony. He will need Valmar's help. The two men forge a new alliance to rebuild the colony. Once again, the Daleks' evil has united enemies.

The two men head for the laboratory where they find Ben and Polly ministering to an unconscious Doctor. He was knocked out in the final surge of power, but he will be fine. He comes to slowly, seemingly unaware of what has happened. Ben tells him that he destroyed the Daleks but the Doctor plays dumb. Valmar examines the power generator and sees that the Doctor did not cut off the Daleks' power but amplified it. He fed in the colony's power at full on top of the Daleks' own static power and blew up all their power supplies. He is impressed, but the Doctor still plays it cool. It is clear that he is revelling in the havoc he has caused.

Valmar and Quinn are less enthusiastic when they realise the full extent of the damage done. The entire power supply for the colony has been destroyed and it will take months before it will be restored. Both men become angrier the more they discover; and the Doctor's impish glee does not help matters. As they turn away to investigate further, the Doctor whispers to his companions that it's time to go. Before Quinn sends them a bill for the damage!

Back in the mercury swamp, the Doctor and his friends head for the TARDIS. The Doctor toodles on his recorder as Ben and Polly discuss recent events. Ben is a bit put out that Quinn was so angry. They did save the colony after all, despite the cost. Besides that, the Doctor was trying to tell them all along of the death and destruction the Daleks would cause. Polly agrees with this, but notes that the Doctor was behaving very strangely - and unconvincingly - when he was trying to tell them. She's not sure that he even knew what he was doing at the start. The Doctor's only reply is to wink and giggle. This new Doctor is certainly very different from the old one. He will take a bit of getting used to, but his impish sense of humour is growing on them both.

They reach the TARDIS and are alarmed to find a Dalek casing sitting outside. Ben's sure it's quite dead and not worth notice. The three of them pile into the TARDIS, the Doctor continuing to pipe away on the recorder.