All is well in the TARDIS as the ship flies through time and space. The Doctor flips switches while Barbara watches. Shortly, he announces that they are approaching a planet and this brings Ian and Susan over to see where they might be. Barbara suddenly jumps back from where she has been leaning on the console, her finger having been burned by something. The Doctor surmises that one of the controls is overheating. Not worried, he sends Susan off to check the fault locator for a clue. The Doctor thinks the problem may have to do with the new combination he tried to sidestep the ship from the middle of the 18th century to the middle of the 20th century.

Susan finds 2 faults registering - QR18 and A14D. Neither means anything to her, but suddenly a klaxon begins blaring a warning. Turning back, Susan sees the main doors opening of their own accord, a brilliant white light pouring in. She shouts a terrified warning and the Doctor is quickly at the controls, trying to halt the materialisation sequence which is already in progress. He shouts to the others to physically close the doors, hoping to minimize the potential damage. Ian and Barbara, joined by Susan, struggle to close the massive doors, eventually succeeding. The klaxon falls silent and the Doctor is in a state of shock. He announces that the materialisation is nearly complete.

Indeed, the TARDIS arrives, wedged between 2 pillars of rock just taller than the light on top of the police box.

Inside, the Doctor collapses into a chair, his companions peppering him with questions. He sends Susan to check the fault locator again. Ian is quick to want to believe that everything is all right. They have safely materialised, haven't they? And everyone is in one piece. But the Doctor dismisses this belief as childish - the doors opened before the ship had properly materialised. Something must have gone terribly wrong but he is quite vague about it despite all the questions. The Doctor gets more and more irritated, but Susan soon returns with good newsthe fault locator registers nothing wrong. Not even a yellow stand-by. Puzzled, the Doctor goes off the check it for himself. Ian and Barbara turn their questions on Susan, who can only say that materialisation is the most dangerous point of their travels and nothing like this has ever happened before.

The Doctor returns, pleased to report that the fault locator shows nothing damaged, but he is still puzzled by the whole business. He apologizes to Barbara for being rude earlier, saying he always forgets the niceties under pressure. He leads the group back to the console to check the instruments. Everything indicates that the outside environment is quite safe. He asks Susan to turn on the scanner. The screen at first is blank, but then suddenly explodes with great force. The Doctor notices the direction of the explosion and likens the manner of it to that of something too big for its frame bursting. It is all part of this growing mystery. But the Doctor still doesn't seem overly concerned and allows Susan to open the doors. He admonishes his companions to be careful - there is no knowing what dangers await them outside. Ian hesitates before going out. He believes the Doctor knows more than he's telling. Indeed, the Doctor answers that the doors opened because the space pressure outside was too great while they were materialising. It is a miracle to him that they came out of it unscathed. With that, he ushers Ian outside to join the others.

They emerge to find the two giant rock formations on either side of the TARDIS and paths leading off at odd angles in 2 directions. It is strange, but not threatening so far. The ship looks fine and Ian again suggests that there was no damage from their ordeal other than the scanner. Susan and Barbara draw their attention to one of the rock formations. There are two kinds of rock - ordinary stone above and something else at the base. The Doctor and Ian think it looks like very rough-grained cement. Whatever it is was used to keep the rock in place, even though it appears heavy enough to keep itself in place. The Doctor suggests splitting up, sending Ian and Susan one way whilst he and Barbara go the other. Against his better judgment, Ian agrees.

It is not long before Barbara notices what appears to be a giant snake hanging down from the rock face above them. The Doctor is quite sure that it's dead but is not sure it's a snake. The skin is dull and brown and the creature has no discernable eyes or mouth. Barbara is more concerned by its fantastic size. She is relieved when the Doctor decides to move on and explore further.

Susan notices a long ovoid object on the ground and she and Ian stop to investigate. It looks for all the world like an egg, but it is far too large even for an ostrich egg. Seeing more ahead, Susan moves on. There is a whole pile of them. However, she stops moving when she sees a giant ant staring at her from the top of the pile. Ian approaches carefully as Susan stands still. Mercifully, the ant is dead. It died while transporting its eggs - natural behaviour for an ant that is being attacked. The others must have been frightened off and this one died very suddenly indeed. Ian is quick to wonder what kind of a world they have wound up in.

Meanwhile, the Doctor and Barbara have circled round their rock formation and found the other end of the dead snake - only it isn't a snake but a huge worm. Except for its size, it could be a perfectly ordinary earthworm. Again the Doctor is ready to press on quickly. He must get to the bottom of this mystery. And for that he needs more information. Barbara remarks on the maze-like layout of these "canyons" they are traversing and this also intrigues the Doctor. While it is maze-like and a bit haphazard, it is not without a pattern. There is an intelligence behind it. But what kind? They continue on.

Ian and Susan have also continued on, finding 5 more dead ants along the way. But their next discovery deepens the mystery even further - it is a large "picture" of night scented stock. Like a billboard, hanging on a giant stake in the ground. The words are written in English, along with the Norwich address of a seed company. Surely this means they are on Earth, but there is certainly something odd about it. Ian suggests some sort of fair where everyday objects have been increased in size.

Not far away, the Doctor has found a large piece of timber leaning against the rockface. But it is perfectly square from top to bottom - cut by a manufacturer. The Doctor accidentally knocks the timber over, nearly frightening Barbara to death. Regaining her wits, though, she notices the top of the timber is rounded and charred. It looks for all the world like a matchstick. The Doctor confirms that is precisely what it is. Now he knows the answer to at least part of the mystery.

Susan, too, is beginning to suspect. And her suspicions are confirmed when she and Ian go round to the other side of the "billboard". There they find a giant matchbox. Ian climbs in to find the corresponding giant matches. Ian is certain they are on Earth and trapped in some sort of exhibition of giant objects, but Susan knows the truth. These objects have not been made larger, but they and their friends have been made smaller. Both Ian and Barbara find this hard to believe. But both the Doctor and Susan are certain they have all been reduced to the size of an inch and are now encountering everyday objects on modern-day Earth.

Unbeknownst to them, the TARDIS has materialised between 2 crazy-paving stones in the garden walk very near a small house.

The Doctor and Barbara head off to find the others. They must return to the ship immediately.

Susan continues to try and make Ian understand. Once the doors opened. The enormous space pressure forced them to reduce in size. It seems fantastic, but everything they've seen bears this out. Suddenly, darkness falls over them and loud crunching noises can be heard. Susan runs for cover, but Ian falls into the matchbox and is trapped. Far above them, the darkness is revealed to be the shadow cast by a man walking toward the matchbox. He picks it up and carries it with him toward the house. Susan peeks out from her cover to find the matchbox gone. She screams for Ian and succeeds in bringing Barbara and the Doctor running. She explains the story in anguished sobs. While Barbara comforts her, the Doctor voices the obvious - yet ludicrous - conclusion that someone picked up the matchbox with Ian inside.

Indeed, Ian is being tossed about inside the dark box, waiting for the terrifying ride to end. Soon it does as the well-dressed man who picked up the box takes a seat on a nearby garden bench and puts the matchbox down. He wipes his forehead from the intense summer heat, unaware of what he has just done.

The Doctor climbs to the top of the rockface, hoping for a better view of their surroundings. He sees in the "distance" the house and the rest of the path leading to it. He also sees the man sitting down reading what appears to be a notebook. He cannot however see the matchbox. As he climbs down, the Doctor is pelted with questions. He silences the women as best he can. He thinks he can return them all to normal size once they return to the TARDIS, but they must find Ian first, despite the overwhelming obstacles they will face. They head off toward the house.

Meanwhile, the man continues reading from his notebook, absently grabbing a cigarette from the packet on the ground beside him. He spots a cat lounging near the front door and calls to it. Getting no response, he goes back to the notebook, finishing shortly. He returns the notebook to his briefcase and reaches for the matchbox to light his cigarette. If he opens it, he will surely discover Ian, but he stops when a new arrival offers him a light.

The new arrival is Forester, a smooth-talking gentleman with steely eyes and a very serious demeanour. He addresses the other man as Mr. Farrow and they shake hands. But Forester seems troubled. He has rushed here at Farrow's request and he hopes that Farrow has "taken no action" as yet. When Farrow tells him that he has written "his report", Forester reacts with anger. He tells Farrow of all the money he has sunk into manufacturing, distribution and advertising for a product called DN6, all based upon the early favourable response to DN6 from Farrow's own ministry. Farrow seems sympathetic but regrets that he cannot give final approval of DN6. Forester thinks this simply means a few more refinements or tests are needed, but Farrow spells out the problem clearly. At first glance, DN6 appeared to be a breakthrough development in the manufacture of insecticides, but the tests have shown that it is totally destructive, killing even the most beneficial insects in any environment in which it is used.

As it all becomes clear to Forester, he can see his massive investment - spurred on by the early promising tests - going down the drain. He will be ruined by this setback, but it is clear that he won't take this lying down. Farrow's sympathy is not unlimited. In fact, he chastises the businessman for not waiting until all the tests were concluded. Forester at first tries bribery, which Farrow turns down flat. He is quickly to beginning to regret coming here at all. His holiday was to have commenced yesterday --- he is taking his own boat on a tour of the rivers of France - but he came out of courtesy to tell Forester and his scientist partner Smithers the news in person. He is going to telephone his ministry immediately, then post his report and head off on his holiday.

Forester tries one more time, asking him to wait until he returns to report to the ministry, but the dedicated bureaucrat refuses. Forester's voice turns harder than ever, refusing to be beaten. Farrow does not like his tone and states that this is science, not business. There is no room to manoeuvre when it comes to something as dangerous as DN6. He turns to go, but Forester stops him by producing a pistol from his jacket pocket.

Down below, the Doctor, Susan, and Barbara are unaware of the drama happening right above them. They encounter a drama of their own as they trek toward the house. A sound of fluttering wings rises above them then stops abruptly. A giant bee falls to the ground before them. Luckily, it too is dead. The women are frightened, but the Doctor is inspired. What chance, he wonders, would humans have in a world of creatures the size of that bee? The Doctor inspects the bee closely, noting a distinctive odour coming from it - the same odour they've all noticed on all of the dead creatures. It must be what is killing them, but Susan notes that it is an indiscriminate killer - affecting bees, ants, and worms alike. The Doctor too thinks it very dangerous, likely capable of killing them as well. He orders no eating or drinking of anything until they return to the TARDIS. Suddenly, they hear a loud explosion echoing all around them, like the roar of a cannon.

Unknown to them as yet, it was a gunshot. The shot that killed Mr. Farrow. Next to the body, Ian emerges cautiously from the matchbox, rubbing bruised muscles. He heads off to look around.

Nearby, the Doctor, Susan, and Barbara continue their journey, progressing nicely. They have encountered even more dead ants. The destruction is of course horrible, but it is lucky for them that the creatures they have encountered are all dead. They wouldn't not have stood a chance otherwise. The group carries on, nearing the house.

Ian discovers the body lying on the ground. The man's eyes are open but he does not respond to Ian's signals. The man is clearly dead. Shortly, the Doctor and the others have found Ian and exchanged information. The Doctor notices the unmistakable smell of gunpowder in the air. The entire group moves off to examine the body, unaware that their movements have attracted the attention of the cat.

Barbara is the first to comment on the sheer quantity of death all around them here. While it is clear that the giant man has been murdered, it is not clear how or why all of the insects have been killed. Even the most beneficial creatures like worms and ants are dead. Surely that's not right. The Doctor agrees, but he puts his own scientific curiosity aside. The important thing now is to get back to the ship and return to normal size.

The Doctor and Ian urge the others to stay completely still and not look into the cat's eyes. One swipe of its paw could smash them to pieces. Shortly the cat loses interest and goes away, but the travellers are not sure where it's gone. They all know that cats can move very quickly and it may be simply waiting somewhere nearby for them to move. The group elects to stay put a while longer. Susan suggests trying to contact the people here for help, but Ian explains that they wouldn't be able to communicate - the giants' voices would only sound like low growls and the travellers' voices would only sound like little squeaks. Besides, Barbara is sure that the giants would take them away as miniature freaks to be studied and displayed. And, the Doctor adds, more importantly, someone in this house is a murderer. They cannot expect to find sympathy here. Barbara wonders if they oughtn't to do something about the murder, but the difficulties in doing this are clear. There is little they can do at their size. Regretfully, all agree and turn to head back to the TARDIS, the can now long out of sight.

However, they are stopped when a shadow falls again on them and the ground shakes with giant footsteps. Ian sees people coming and the travellers start to run. Barbara trips and Ian must force Susan away with the Doctor while he helps Barbara. They head off in the opposite direction to the nearest cover, and the Doctor and Susan must watch helplessly as the others try to evade the giants. Susan wants to go and join them, but it is too late now. The Doctor drags her to a nearby pipe to wait and watch.

Ian and Barbara have found the only place to hide, a briefcase lying on the ground. They dive inside just as the giant feet reach them.

Forester returns to the scene of the crime, bringing with him Smithers the scientist who created DN6. Together they look over Farrow's body. Forester concocts a story that Farrow pulled a gun and announced he was stealing the formula for DN6 for his own gain. Forester struggled with him for the gun, which went off and killed Farrow. But it only takes Smithers' cursory examination of the wound to see that the story is an obvious lie. The police will see through it as well. Forester comments on how calm Smithers seems to be, testing the waters to see if he can reveal the truth. But it is only the fact of death that Smithers is calm about - having seen starving people all over the world. He himself is surprised at Forester's coolness, who says he is too busy working out what to do next to feel guilty. The truth of what happened is unspoken between them, although both know. Smithers lashes out in anger, certain now that years of research are lost and Forester is to blame. He gave his life to the project and now all of it is ruined with Farrow's death. But Forester has already moved forward. He announces a plan to tow Farrow's boat and the body out to see and dump both. His disappearance won't be noticed for weeks and there will be nothing to connect him to DN6 after that. Smithers starts to protest, but sees for a brief blinding moment that this is the simple answer to the problem. No Farrow, no halt to DN6. He decides to turn a blind eye and leave everything to the devious and determined Forester. All Smithers cares about is the benefit that DN6 will have to halt starvation in the world. He cannot let anything stop that. Thus convinced - for now - Smithers leaves the rest to Forester. Together, they'll move the body, but first Forester decides to take Farrow's briefcase into the lab. He places it on the lab bench, unaware that he has just transported Ian and Barbara far away from their friends below.

Ian and Barbara emerge, badly shaken from their bumpy ride. Barbara massages a battered ankle. Ian soon notices the ceiling far above them, indicating that they are now indoors. And the Doctor and Susan are outside -- a very long way at their present size. Barbara assesses her bumps and bruises - caused by a flying paper clip in the briefcase - and wonders if there's any water around with which she can bathe her ankle. Ian goes off to find some.

Meanwhile, Forester and Smithers return to the grim task of moving Farrow's body to a safe place for the time being. Smithers suggests the store room. Farrow was not a thin man and it takes quite an effort for both of them to drag his dead weight. They do not even notice the two tiny figures near the drain pipe who duck as they walk past.

The Doctor and Susan emerge from hiding once the giants are gone. They are near the outlet to a drain pipe which runs up the side of the house. Susan is certain that she saw one of the men pick up the briefcase in which Ian and Barbara were hiding. She is less certain that he took it inside. The Doctor ventures into the drain pipe, coming back out again straight away choking from the powerful chemical smell. He proposes that they climb up the inside of the pipe to try and get into the house. The pipe is corroded inside so there are plenty of hand and foot holds. Susan is worried that it will be too hard a climb for her grandfather, but the Doctor tells her they must try. In this world, they only have one another to help them. Ian and Barbara are counting on them so they must try to find them. Susan agrees and leads the way.

Ian returns having had no luck finding water. All he saw was what appeared to be a giant gas tap. Barbara thinks she is OK to walk and tests her ankle successfully. They head off in the other direction to explore further.

The early part of the climb goes easily for the Doctor and Susan. Hand and foot holds are plentiful and their strength holds. Susan is worried about her grandfather, but he urges her onward and upward.

Ian and Barbara run first across a giant rack of test tubes and then a pile of giant seeds in a dish. Ian turns away to look around and does not see Barbara pick up one of the seeds, which she determines to be wheat. However, her hands are soon coated with some sticky residue. She borrows Ian's handkerchief to try and get it off. Meanwhile, Ian has found a book of litmus paper. Having handled the tiny papers many times, he has a very good idea now of their current size as well as the enormity of their predicament. This is obviously a laboratory of some sort, likely having to do with the chemical that killed all the insects in the garden. He repeats what the Doctor said beforewhat killed those insects could easily kill them too. Barbara suddenly remembers the Doctor's admonition not to touch anything in this world and realizes with horror that the substance she has been trying to remove from her hands smells exactly like the substance they found on the bee. In goes on, stating the obvious safeguard of not touching anything either. He knows how dangerous some insecticides can be and this one seems even more deadly. Barbara, feeling quite stupid for having picked up the seed, decides not to tell Ian what she's done. Instead, she urges them on to find the others and get back to the TARDIS. If they can do that quickly, she knows she will be fine. Oblivious to her plight, Ian racks his brain for a solution. He sees Barbara getting more and more upset, but thinks she's only despairing of ever getting back. He reassures her they will and suggests looking for some string on which to climb down to the floor. Barbara, overcome with the fear of dying like all the insects, mocks the absurdity of the idea and the situation that they face It's all so ridiculous! Ian tries again to reassure her, suggesting stringing paper clips together to form a ladder. Barbara brightens at this idea, suggesting also that whilst they look for paper clips in the briefcase they might find more information on this insecticide. Ian admits this is a possibility, but thinks getting down is more important to them. Little does he know.

Susan and the Doctor continue their mountainous climb, but the Doctor is beginning to tire, his hands red and raw from the chemicals in the pipe. Still, he carries on as quickly as he can.

Ian has climbed to the flap of the briefcase and is struggling with the clasp. Barbara watches from below. She is at first unaware that an enormous fly - this one quite alive - has landed just behind her. Ian completes his task, opening the briefcase so they can search it more easily, but gets no response to his calls for Barbara. She has seen the fly and stares at it transfixed. Overwhelmed with fear and the first effects of the insecticide, Barbara faints dead away. Ian arrives and tries to wake her, but he too is mesmerized by the sight of the giant fly. Suddenly the fly takes off in a flurry of wings, startled by something. Ian soon hears it too - loud deep sounds indicating the arrival of the giants. He grabs Barbara and carries her off to a hiding place.

Smithers enters the lab, closely followed by Forester. The little scientist is acutely aware of Forester's coolly intense gaze. He is trying to see if Smithers will truly be able to go along with their plan or if he will crack under the strain. For his part, Smithers only intends to get a cloth with which to clean the blood off the flagstones outside. But his mind is working overtime. He is aware that when DN6 becomes a success, Forester will easily be able to put this little episode out of his mind. But he is only going along in order to see the experiment through to completion - to save lives. It is clear that Smithers is unaware of Farrow's findings and Forester will do whatever it takes to see it stays that way. He has been playing on Smithers' altruistic determination to see DN6 produced in order to make him an accomplice to this murder. Smithers pretends innocence, but Forester believes they are both alike - both will stop at nothing to achieve their goals.

Susan and the Doctor have completed their climb, barely surviving the chemical stench and the grueling exertion. Susan tends to the Doctor as he recuperates from the strain. They have come up in the bottom of a sink and rest near the drain hole. The giant plug sits on its chain beside them. Susan tells the Doctor she thinks she just heard the giants leaving the room and suggests they go looking for Ian and Barbara as soon as they can. But, noticing the odd echo of their voices in the sink, the Doctor as a better idea.

Barbara comes to with a start and Ian calms her. He is glad she's all right. He tells her that the fly is now dead, killed instantly when it landed on the pile of wheat seeds. Barbara's face goes white and she goes over to see for herself. The creature is completely still now, atop the seeds. Ian points out the insecticide glistening on its legs and reiterates how lethal the stuff must be. All denial now gone from her mind, Barbara dissolves into tears and starts to tell him what she's done. But she stops at the sound of a voice - a normal voice. It is Susan calling loudly to them from somewhere nearby. They can hear her clearly but she cannot hear them respond. She simply keeps calling. Barbara tells Ian not to worry about what she was going to tell him earlier and hurries off to find the source of Susan's calls. Ian follows.

The Doctor urges Susan to continue. She won't hear a reply but the sink is acting to magnify her voice, thus making it audible a long way off. Susan worries that the giants may hear, but the Doctor assures her that only dogs will be able to hear their voices at this pitch. Susan starts calling again and shortly Ian and Barbara appear above the rim of the sink. They are all overjoyed to be reunited. Marvelling at their friends' climb up the sink pipe, Ian and Barbara start to climb down the plug chain.

Meanwhile, Smithers completes the grisly task of cleaning the blood from the flagstones. He sits heavily, worn out by more than just the heat and the effort. Forester finishes by grinding dirt onto the stones with his heel to cover the stains. Then they head inside to wash their hands...in the lab sink!

Hearing the sounds of approaching people, the travellers hurry for cover, Susan and the Doctor back into the drain and Ian and Barbara back up the chain and into hiding in the briefcase.

Unaware of all this activity, Smithers and Forester roll up their sleeves. Heading toward the sink, Smithers is halted by the sight of the fly on the seed pile. He can see that it died instantly as soon as it came in contact with DN6. He sees it, but the implications escape him. Instead, he thinks of the beneficial effects DN6 could have against locust plagues. He is delighted but wonders how Farrow could have hoped to get away with "lying" about the effectiveness of the new product. It is clear that Forester has lied to him about the content of Farrow's report, a report which Forester himself will amend before sending it in to the ministry as planned. Again, Smithers chooses to stop listening. All he can think about is the boon that DN6 will be to mankind. What actions Forester takes he does not want to know. He turns instead to the sink, opening the tap and putting in the plug.

Ian and Barbara emerge from the briefcase cautiously. They can see in the distance one of the giants running water and washing his hands in the sink. They fear for their friends' lives. In the drain pipe, the Doctor and Susan can clearly hear the running water as the sink fills, an ocean rising above their heads.

The water pours down the drain, but the Doctor and Susan hide safely in the overflow pipe. They realize how close they came to death - any more water in the sink and it would have poured down upon them.

Ian listens carefully to the low sounds made by the giants. He is pretty sure from the sound of it that they have left the room. Barbara thinks it unlikely the Doctor and Susan could have escaped drowning, but Ian stirs up his courage. They must go and find out. They go to the sink and climb down the plug chain, which one of the giants must have returned to the sink bottom after draining the water. At first there is no sign at all of the others in the darkness of the drain hole. But just when they are about to give up, Susan emerges from the drain, laughing in joy at their survival. The Doctor joins her, nothing that he's very difficult to get rid of!

Meanwhile, in another part of the house, Forester has made the necessary amendments to Farrow's report. Despite his desire not to know, Smithers is with him all the while, sitting restlessly by. The scientist is growing more nervous by the minute and he jumps when Forester reaches for the telephone. Forester knows that Farrow was going to phone his head of department and now Forester must do it in his place. Smithers is horrified, certain this will give them away and condemn his precious project, but Forester is very cool indeed. He even knows the number and name of the person to speak to in Whitehall, having dealt with the ministry for a long time over this. He places a handkerchief over the receiver and asks for Mr. Whitmore. He is encouraged when the secretary seems to believe he is Farrow.

However, the operator who switched the call - an old busybody named Hilda Rowse - is listening in. She has taken calls from Mr. Farrow numerous times and she is not at all convinced that this is him. Her husband Bert takes note of this as well.

Connected with Whitmore, Forester sings the praises of DN6. Whitmore is surprised that "Farrow" is so enthusiastic, but Forester chalks it up to the exciting promise of the new insecticide. He promises to send in the report, endures some banter about "Farrow's" holiday, and then pushes for the authorisation for DN6 to go ahead. He assures Whitmore he'll "tell Forester", then he rings off, smug and confident. As soon as the report is in, the authorisation will be given.

Meanwhile, the direction of the travellers has changed somewhat. Feeling emboldened by their good luck so far, they have climbed out of the sink and are exploring the lab bench. They have found what looks to be a giant notebook. One of the giants must have taken it out of the briefcase. A quick examination shows that the writing on it is a formula, perhaps for the deadly insecticide all round them. Barbara - still keeping her contact with the stuff a secret - suggests they might be able to find a cure for it, but her friends think this is a useless cause as one only needs a cure if someone has been poisoned. They are thinking instead of finding some way to stop it being produced. Unfortunately for Barbara, her friends are much more interested in this at the moment than in returning to the TARDIS.

Using a method of mapping out the giant document one piece at a time, the Doctor recreates the page on his own notebook in a size he can read. It is quite clearly an insecticide, not only incredibly deadly but also everlasting. Unchecked, it will seep into the soil and the water and contaminate everything. The Doctor even thinks it could get through the skin and into the bloodstream of humans. Hearing this and knowing her predicament, Barbara reacts angrily, wondering why they are just sitting around talking and not doing anything. She realizes how harshly she's spoken and apologizes, saying she's giddy through lack of food. Unfortunately, they cannot eat anything here given the presence of the insecticide. However, the water in the sink should be potable and it may do them all some good. They all head off together, the Doctor curious about a telephone he saw earlier. He thinks that it may be the solution to all of this.

Indeed, they do find a phone, towering above them on the lab bench. However, a very long flex is piled next to it and appears to be climbable. Barbara and Susan bring over a large cork stopper they found, thinking it could be used to hold up the heavy receiver for them. Ian is concerned by Barbara's flushed face and extreme fatigue. She knows it is the increasing effect of the insecticide but passes it off as hunger and urges him not to make a fuss. She sits to rest while Ian and Susan begin their climb up the flex. When they get part of the way up, the Doctor asks Barbara to bring over a second cork while he passes the first up to Susan. Barbara does so wearily, carrying the giant cork with some difficulty. She returns to her rest at the Doctor's urging.

Ian reaches the cradle of the phone and takes the first cork from Susan. Susan brings the second and the Doctor follows her up. It is a long moment before Barbara is able to climb up and join them. Ian, Barbara, and the Doctor use their combined strength to lift one side of the heavy receiver and Susan wedges the cork under it. The effort is almost too much for Barbara, who staggers a bit as she crosses to the other side. The process is repeated on the other side and soon the receiver is completely off the hook. The engaged phone registers as an insistent buzzing at Hilda Rowse's station. Her husband Bert beckons her to answer it and stop the racket while he's trying to eat. She does so, but hears nothing at all on the other end of the line this time.

The Doctor, Ian, and Susan are shouting with all their lung power into the phone, but it is of no use. Barbara, listening on the other end, hears a short growling sound and then nothing more in response. Unseen by the others, Barbara staggers again and falls to her knees. The others lament their failure. The Doctor was hoping that the phone's voice amplification might make their voices loud enough for the giants to hear. But he was wrong. Ian refuses to give up though, and goes to tell Barbara that they are going to try again. He finds her more flushed and worn looking than ever and is alarmed. She tries again to pass it off as fatigue, but when Ian tries to take her handkerchief to get some water, she is forced to keep it from him. She starts to tell him the truth finally, but passes out before finishing.

Susan and the Doctor join them and quickly discover the insecticide on her hands and the handkerchief. She has contacted the stuff and is now poisoned. Ian recalls when she borrowed his handkerchief - when they discovered the pile of wheat seeds - and reasons that was when she must have touched the insecticide. Ian and Susan are badgering the Doctor to tell them what can be done to save her when Barbara's eyes open. They tell her they know what has happened and chide her gently for not telling them. She is worried she is dying, but the Doctor tells her this "attack" was only temporary. She is not yet in imminent danger, but things will continue to get worse rapidly.

The Doctor draws Ian aside and tells him that they must return to the ship and try to restore her to normal size. Right now, her protective cells are too small to cope with the poison, but the dosage in her bloodstream will shrink by 70 times - completely harmless - once she regains her normal size. Bu t they must get back to the TARDIS. Ian tells Barbara they'll be heading back and that she must steel herself for the long journey. Privately, he seeks assurance from the Doctor that he can restore her size and save her. The Doctor tells Ian with certainty he can, but inwardly he is not nearly so confident.

In the house, Forester has picked up the phone but cannot get an outside line. Something is wrong.

Back in the lab, Ian is flabbergasted to learn that Barbara refuses to return to the ship until they do something to stop this insecticide. She reasons that if they leave, saving only themselves, they will be unable to return to this time and place and save their world from the deadly poison. The Doctor agrees with her, as does Susan. Even though it may mean Barbara's death, Ian is forced to go along.

Smithers tells Forester there is another telephone in the lab which may be off the hook. He goes out to check on it, saying in passing that he also wants to check Farrow's notes on DN6 while he's out there. Concerned that Smithers suspects something and may be after the truth, Forester checks his gun is loaded and hurries after Smithers.

The Doctor has looked all round the lab bench and has come up with a plan. They will try to start a fire! This will either cause enough damage to the lab to stop the experiments or will attract attention here. With any luck, any new arrival will find the body of the murdered man. It may be a long shot, but it is their only chance. However, actually starting the fire is the hardest part of all. Ian remembers the gas tap he saw earlier. This would be ideal, if only they can turn it on. The group is startled by the sounds of the giants returning. They head for the water tap on the sink in order to hide themselves, needing to dodge constantly to stay out of sight.

Forester checks the phone and finds the corks holding up the receiver, baffled as to how they got there. But Smithers notices instead the smell of DN6 in the lab, much stronger than before. With its receiver replaced, the phone suddenly rings and Forester snatches it up. It is Hilda Rowse calling, checking that the line is now working again. Following up her earlier hunch, she manages to ascertain that she is talking to neither Smithers nor Farrow, but a third party. She then makes up an incoming call for Mr. Farrow and asks that he be put on the line. With nothing else for it, Forester covers the receiver with a handkerchief and takes "the call" as Farrow. Hilda is convinced that it is not Farrow but the third man again, deliberately pretending to be Farrow. A few more words and Bert is convinced as well. Hilda claims the incoming caller has broken the connection for some reason and rings off. Hilda's plan has worked as Bert decides to go to the house to have a look round. He dons his constable's helmet and heads off.

Forester wipes his brow, certain he's had a close call and not at all sure he's escaped it completely. But there are more pressing things to deal with. Looking round, he notices Smithers has gone. The scientist is outside in the garden, digging through the soil where DN6 was sprayed. A look of horrified realisation creases his face as he does so.

With the giants out of the room, the travellers get quickly to work. The Doctor, Susan, and a weakening Barbara loosen the gas tap while Ian wrestles a giant match from the box on the bench. Susan joins him and together they make plans to light the match. They'll use it like a battering ram and run it against the matchbox at an angle. Meanwhile, the Doctor and Barbara have shoved a giant tin in front of the gas jet. The Doctor has realized that this is an aerosol can. When heated, it will explode with all the force of a 1000 pound bomb. They must make plans to get well clear. Unbeknownst to him, the tin is full of DN6!

Smithers has found evidence of all the dead creatures in the garden - good and bad alike. He knows now what Farrow found and he knows his life's work is ruined. Forester knows he has lost Smithers' cooperation and will not let it stop him. He stands menacingly over the devastated scientist.

Meanwhile, Ian and Susan are having trouble lighting the match. It is much heavier and harder to manoeuvre than it looks. With the Doctor and Barbara urging them on, they give it another go. This time the match lights in a blaze of fire. The Doctor and Barbara turn up the gas jet to full and Ian and Susan guide their match forward once the others are safely out of the way. The jet lights and spews fire toward the spray can.

Outside, Forester concludes his story to Smithers - the truth of what Farrow found out and why he was killed. With so much money invested in DN6, Forester had to see it through no matter what. He proves this is still the case by pointing his gun at Smithers.

The time travellers watch the can heat up, preparing themselves to take cover when it explodes. There will be a lot of metal flying around. Susan and the Doctor take a moment to recall a similar experience during a zeppelin air raid long ago.

Forester forces Smithers inside at gunpoint, the scientist protesting all the way. DN6 is not a boon to mankind - surely Forester must care about this - it is more dangerous than radiation. But Forester only cares about money and he will not be stopped. He orders Smithers to get Farrow's briefcase from the bench, but as Smithers turns, he sees the gas jet and the spray can. Forester sees it too and makes a dash for the can. As he does so, the can explodes in his face. He screams and covers his burning eyes, dropping the gun as he falls to the floor in agony. Smithers grabs the gun and holds it on his former partner, his hands shaking. But Bert Rowse - PC Rowse - arrives and takes the gun away.

Delighted by their efforts at troublemaking, the Doctor hurries his friends down the plug chain and into the sink. Barbara hasn't much time left. The Doctor takes a second to grab one of the giant wheat seeds scattered now across the bench. He wraps it in his cloak in order to bring it with him. When Ian asks why, the Doctor promises him a surprise.

Rowse helps Forester to his feet. Already the sting in Forester's eyes is subsiding. He'll be all right eventually. Rowse orders Smithers to turn off the gas and then readies the requisite "few questions" for the men.

The time travellers reach the TARDIS without incident and the Doctor is swiftly at the controls attempting to repeat in reverse all the moves he made before they arrived here. He instructs Ian to move the giant wheat seed to a nearby table. Barbara is unconscious in a chair with Susan watching over her. The lights inside the ship dim and the Doctor paces grimly. The TARDIS dematerializes from between the crazy paving stones.

Shortly, the Doctor's mood brightens. His plan appears to be working. For proof, he points to the wheat seed, still very much oversized but now shrinking rapidly. Another moment and the lights return to normal. The Doctor declares victory with a gleeful shout. Ian is confused, thinking the seed has vanished, but the Doctor shows him the truth. The seed is there, but it is now the proper size, barely visible between the Doctor's finger and thumb.

Barbara starts to come to and is very thirsty. After a drink of water, she begins to feel much better. The Doctor is pleased with her rapid progress. He tells her that their plan worked - he is certain he saw a policeman come into the lab as they were leaving. He then shows her the tiny wheat seed to prove that they are back to their normal size. He sends all 3 of them off for a good scrub while he goes to check the instruments.