1. Alan Turing
December, 1944. While bicycling in Oxford, Alan Turing encounters an odd man talking to a statue of a griffin and apparently expecting it to talk back to him. Before Turing can learn more about this mysterious, charming Doctor, he is called to Bletchley to decode a transmission from Dresden, which appears to be encoded in a brand new cipher. No closer to a solution after several days’ work, Turing accepts an invitation to tea from the Doctor, but to his surprise the Doctor seems to know all about Turing’s top secret work and the mysterious new code. The Doctor points out that although the code was transmitted from Germany, this does not necessarily mean that the codemakers are German...

The Doctor invites Turing up to his room at the inn, claiming that he is having a mathematical problem with what seems to be a large blue wardrobe. However, when the Doctor finds that the inside of the box is smaller than the outside, he flies into a rage, and he and Turing are both kicked out of the inn. Turing impulsively offers to let the Doctor stay with him at Bletchley until he can find rooms elsewhere, but that night, as Turing replays the mysterious transmission, the Doctor listens in -- and abruptly runs screaming into the night. The strange behaviour which Turing had accepted when the Doctor was actually there makes no sense when he has gone, and though conflicted, Turing reports everything to his superior, Hugh Alexander. When the Doctor next tries to make contact with Turing, MPs are waiting to arrest him.

The Doctor, when questioned, claims to have no memory of who he is or where he comes from, but insists that he be allowed to help crack the code. He feels an affinity with the codemakers, having sensed great loneliness, more than he could bear, in the transmission. A man from Military Intelligence, who calls himself White, releases the Doctor and agrees to take him and Turing to the liberated Paris to try to get closer to the codemakers. In Paris, they meet Colonel Horatio Elgar, a remarkably stereotypical English officer who claims to have worked with the French Resistance. That night, the Doctor and Turing discuss the code, which the Doctor believes may be speech in a language either invented as another level of coding, or never meant for human ears. He and Turing see White returing to the hotel with a woman who flees upon spotting the Doctor. The Doctor feels as if he should recognise her, or something about her...

The Doctor and Turing manage a partial translation of the coded message; in order for the exiles to resume their status, two of something must be removed using local resources. Only twice before in the Doctor’s memory has he had a chance of finding out who he is, and getting back to what he used to do; this is the closest he has ever been. He insists that Elgar allow him to visit Dresden and contact the codemakers, but Elgar flatly refuses and instead orders him to encode a reply, obviously intending to lure the codemakers into a trap. Frustrated and furious, the Doctor sets to work, but Turing isn’t sure he can trust the Doctor to do what Elgar has asked, and goes to White for advice. “White”, depressed and despairing for the human condition, admits that his real name is Greene, and claims that the codemakers are Nazi guards from death camps where millions of Jews are being systematically slaughtered; Elgar intends to lure them into a trap and learn the location of the camps. This explanation doesn’t make sense to Turing, but Greene loses his temper with Turing for treating the death of millions as merely another clue in a logical puzzle, and Turing realises that he will find no help here.

Turing spots Elgar meeting the woman they saw with Greene the previous night, and overhears her telling Elgar that although they don’t know who or what the Doctor is, he must be killed if he poses a threat. Unsure who to trust, Turing warns the Doctor what he has heard, but at the same time, decides to decode the Doctor’s reply to the codemakers and find out what he is really saying to them. Before he can do so, there is an explosion in Elgar’s room, reducing the room and its sole occupant -- the mysterious woman -- to ash. The Doctor disappears, and Elgar, apparently believing that the Doctor is responsible for his colleague’s death, orders Turing to turn him in if he makes contact again.

Turing goes for a walk to clear his head, and finds the Doctor in a cafe, speaking with a young man named Bernard who seems to resent the Americans who have liberated Paris. Is this due to the Americans’ arrogance, or is the Doctor speaking with a former Nazi collaborator? Still unsure what to do, Turing returns to the hotel to find that Greene and Elgar have already left and have made arrangements for Turing to return to Bletchley. On his way back, however, the Doctor contacts him once again, and reveals that Bernard -- who is indeed a former collaborator -- is willing to smuggle them over the border to Switzerland, so they can reach Dresden and contact the codemakers before Elgar springs his trap. Turing finally chooses his side; he will trust the Doctor, and help him to stop Elgar.

2. Graham Greene
Sierra Leone, 1942. British spymaster Graham Greene travels to the village of Markedo to speak with his agent Cray, but when he arrives the village is deserted -- apart from three strangers with pure white, unblemished skin, who speak in a sing-song language unlike any he has heard before. Greene takes the strangers to the neighbouring village of D’nalyel, where he finds the people of Markedo, who claim to have fled in terror after seeing demons descend from the sky. Cray claims that the French believe that the English have been testing a new weapon in the sky above Markedo, but before he can elaborate, SS troops storm D’nalyel, demanding to know about the strangers and the “secret weapon”. Greene hears shots and screams outside, and emerges to find the Germans running from two figures swathed in flames, which melt away, leaving nothing at all like human remains. There is the sound of violence in the darkness, and Greene never sees the Germans or the strangers again.

Months later, a man named the Doctor arrives in Sierra Leone, apparently desperate to find out the truth to the rumours about Markedo. They find no further evidence of otherworldly activity in the village, and when the Doctor asks Greene what it means to be human, Greene -- who has spent his life looking for miracles -- comes to suspect that the Doctor has very personal reasons for asking. Somehow feeling that he can trust the Doctor, Greene books passage for him back to England. He too eventually returns to England to take over the running of agents in Portugal, but becomes disillusioned when he is forced to send loyal men to their deaths in order to prevent the Germans from realising that the British have cracked the ENIGMA code. He also meets a beautiful woman named Daria, and in the course of their conversations he tells her about the incident in Africa and the stranger called the Doctor.

When the Doctor is arrested in Oxford, he asks to speak with Greene, and explains that he’s been tracking the strangers’ movements ever since he left Africa. He now believes that they killed the SS team and took their places, and that they are the ones sending the code from Dresden. Greene agrees to help the Doctor get close to them, but as he does so he gets a call from Daria -- who is also in Paris, working with Elgar. As the Doctor and Turing discuss the code, Greene contacts Daria once more. But when she runs in shock from the sight of the Doctor, Greene, still seeking miracles, suspects that he has stumbled across a war in Heaven -- and that the Doctor and Daria are on opposite sides.

Unsure who to trust, Greene agrees to plant a device in Elgar’s rooms which the Doctor claims will generate quantum interference patterns and enable him to track Elgar’s movements. Daria then contacts Greene once again; she is trying to blend in with humans in order to conduct her mission, and is becoming more human herself as she does so. Thus she is feeling lonely, and she takes Greene to Elgar’s rooms to make love. But the Doctor’s device seems to affect her adversely, and she flings Greene out of the room moments before she spontaneously combusts, reducing the room to ash. The Doctor claims not to have expected this, but Greene doesn’t believe him; as far as he’s concerned, the Doctor has tricked him into murdering his lover, and must be on the side of evil.

Greene arranges Turing’s return to Bletchley, but insists upon accompanying Elgar to Dresden to entrap the codemakers. Elgar disguises himself as a Nazi in order to cross the lines, but his disguise is a bit too perfect, and once again Greene finds himself uncertain which side he is on -- especially when Elgar strikes an innocent civilian with his stolen car while trying to escape a suspicious Nazi officer. Elgar’s personality seems to change to suit his objectives, and he claims that his sole purpose in existence is to carry out the orders he has been given. He insists that the codemakers are the truly dangerous ones -- but to Greene, Elgar seems more like a machine than a man.

Upon arriving in Dresden, Greene and Elgar are arrested by an SS officer and taken to an abandoned church, where the Doctor is waiting for them. Turing is also there, working with the Doctor to help the strangers adapt human technology to build a device which will enable them to return home. He insists that Daria’s death was an accident, but Greene doesn’t believe that, especially when Allied planes begin to firebomb Dresden -- and the Doctor insists that they leave Elgar tied up in the crypt. Greene rushes back into the burning church and releases Elgar, but outside, the Doctor apparently tries to kill Elgar with the same device that killed Daria. Furious, Greene shoots at the Doctor, who falls.

As the firestorm consumes Dresden, Turing and Greene seek shelter in the cellar of a nearby pub, but Elgar follows them, his arm having melted away to reveal a metal skeleton. Turing flees in terror, still believing that Elgar is the enemy. Elgar and Greene follow a passageway from the cellar to the canal, where they see the Doctor’s body being dumped into the canal some distance away. Elgar congratulates Greene and tells him that he will have to kill the strangers if Elgar ceases to function, and Greene realises that Elgar has no sense of death as a state of transition or an end to existence; he only considers it as yet another element, an event or tool to be incorporated into his orders. Greene despairs as he realises that he has chosen to fight on the wrong side.

3. Joseph Heller
Joseph Heller is pretending to be mad when the Doctor first approaches him with an offer; if Heller steals a plane and flies him to Dresden, then the Doctor will get him out of the war. Heller refuses, but his pretense is eventually seen through and he is sent back into action. After numerous pointless and life-threatening missions, he finally cracks for real and returns to base without lowering the undercarriage, crashing the plane and injuring his rear gunner. The Doctor shows up at Heller’s court-martial to make the same offer, and this time, Heller has no choice but to accept. The Doctor thus gets Heller cleared of all charges.

After Daria’s death in Paris, the Doctor attempts to smuggle himself and Turing across the border with the help of the French collaborator Bernard, but Elgar warns the Germans to expect them. The Doctor and Turing escape, but Bernard ends up dead. The Doctor is therefore forced to revert to the original plan, which is how Heller finds himself piloting a stolen plane to Dresden. They are shot down in mid-air, and make their way to an abandoned church where the strangers are waiting, having received the Doctor’s reply from Paris. The Doctor and Turing explain to the bewildered Heller that the strangers intend to encode themselves into quantum fluctuations and transmit themselves away from Earth; however, Elgar is interfering with the process. The Doctor thus plans to trap Elgar in the crypt, where he will be safe from the firestorm but the shockwaves of the carpet bombing will cancel out the interference which is keeping the strangers trapped.

Heller reluctantly disguises himself as an SS officer, “arrests” Elgar and Greene and takes them to the church. The firebombing begins, but Greene rescues Elgar from the crypt, putting the Doctor’s plan in jeopardy. The Doctor tries to “disable” Elgar with the device that killed Daria, but Greene shoots at him, and Elgar escapes when the Doctor falls, pretending to have been shot. Greene and Turing flee in the confusion, and Heller, the Doctor and the strangers take shelter in the crypt as the bombers pass overhead. Eventually the bombing stops, but Elgar’s presence is still interfering with the quantum resonator... which means that in order for the strangers to escape, Elgar will have to be killed.

Turing arrives and tells the Doctor that Elgar and Greene are hiding in a nearby pub. The Doctor has the strangers take a corpse out of the burning streets, dress it in the Doctor’s clothing and dispose of it in the canal as a decoy. He, Heller and Turing then disguise themselves, get close to Elgar, and use the Doctor’s device to burn him away just as it did Daria earlier. Heller hears the screams as Elgar dies, however, and realises that, much as Turing might want to convince himself that they were merely destroying a machine, they have killed a living being.