The Doctor bundles Jamie inside the TARDIS as the lava from the Dulcian volcano flows toward them. The Doctor hurries to the controls to try and get them out of here while Zoe admires the beauty of the eruption on the monitor. However, there is a problem with the console. The fluid links are overloading and soon the console room is full of smoke and choking mercury vapour.

Jamie becomes more and more panicked as the lava gets even closer. It's nearly up to the TARDIS! To his horror, the Doctor joins Zoe in admiring the unique beauty of it all. He doesn't buy the Doctor's assumption that they're safe inside and urges him to try and take off again.

At first, it looks as if all is well, but soon the fluid links are overheating again. The Doctor struggles to save them while Jamie gazes in horror at the scanner. The lava is beginning to engulf the TARDIS. The fluid links are saved but there is little the Doctor can do to get them out of here. Zoe joins in Jamie's panic and urges the Doctor to think of something. He mentions an "emergency unit" but is loathe to use it. He says it moves the TARDIS out of tie and space - out of reality all together. He seems quite fearful of the consequences, but Zoe and Jamie's concern persuades him.

He fetches the small device from a cubby hole beneath the console and inserts it into a socket. But he hesitates before activating. He repeats that he doesn't know what will happen but Jamie literally forces his hand. Jamie shoves the device home and it activates. Strange noises fill the air and the ship judders violently.

Outside, the ship disappears from beneath the flood of lava engulfing it.

Inside, the vibration and noise stops. It is very very quiet inside the TARDIS. Jamie is pleased. They're out of danger. However, the Doctor now seems quite worried. None of the meters on the console are registering anything at all and the scanner is a white blank. He is anxious to begin work on the TARDIS controls immediately. He tells a curious Zoe that they are not in flight but that outside the ship is nothing. They are "nowhere" at all. It sounds quite ominous.

The Doctor heads off to the power room, leaving his companions to ponder the meaning of these words. Jamie is little concerned and goes off to change clothes. Zoe heads off to do the same.

A short time later, she arrives in the power room - resplendent in a spangly catsuit - to talk to the Doctor. He seems quite nervous as he works, immediately assuming that something's wrong when she enters. Zoe reassures him and tries to ascertain the source of his fear. He says he only worries about the unknown, but Zoe thinks there is little to fear from a world of "nothing". The Doctor says that the emergency unit has an in-built mechanism to warn them of danger whenever they are out of normal reality, proving to him that it is dangerous to be here. To Zoe, the fact that the warning hasn't sounded proves to her that it's safe. Her curiosity about the outside world is very evident and the Doctor does his best to warn her against it. This is a dimension about which they know nothing. There are forces outside which could be very dangerous indeed. No one is going out.

In the console room, Jamie stares at the blankness of the scanner screen. As he watches, a vision appears. It is the highlands of Scotland. Jamie's home. He is well-pleased at the sight as he hasn't seen his home in a very long time. He can even hear the strains of a bagpipe.

Zoe arrives and he tells her excitedly of what he's seen. However, when she looks she can see only the blank white mist. She is very sceptical, even though Jamie insists the vista is only obscured by a typical highland fog. Zoe repeats the Doctor's warning but Jamie is sure they've landed in Scotland. He checks the console for warning lights and sees nothing. This is proof enough for him.

As Zoe watches the scanner, another vision appears. This is a thoroughly futuristic metropolis, uncountable high-rise buildings spreading out to the horizon. It is Zoe's home city. She is sure of it, and equally certain that Jamie just mistook it. Like Zoe before, Jamie can see nothing when he looks at the scanner.

Between the two of them, they're sure that something is out there. The Doctor was wrong and they really have landed somewhere. Zoe is ready to go outside but Jamie wants to get the Doctor first. He hurries off. As soon as he's gone, Zoe's vision reappears and she becomes even more determined to go outside. She calls to her friends to hurry but there is no response. She rashly opens the doors and calls out again. The vision persists and she can no longer wait. Despite the fact that there is only a misty void outside the doors, Zoe leaves the ship... and promptly disappears.

The vision on the scanner disappears as well.

Jamie explains to the Doctor that they've landed. He's sure it's Scotland, despite what Zoe said she saw. She must be mistaken. The Doctor sees through all of this and is very concerned. Both of them saw different things - both saw their homes. He runs from the power room to the console room.

The Doctor is horrified to see the doors wide open and Zoe gone. He has realised that the pictures on the scanner were put there deliberately to tempt them. Someone or something wants them to leave the safety of the TARDIS.

Suddenly the emergency unit begins beeping and flashing, the first indication of danger in this strange area outside reality. They have very little time. Rashly, Jamie runs out after Zoe. He, too, disappears in the mist. A second alarm begins flashing and the Doctor returns to the console. There is little he can do.

Shortly, another noise fills the room, like the rising roar of an aeroplane engine. It seems to be attacking the Doctor's very mind. He puts his hands over his ears, trying to shut it out. He calls out to whomever is controlling it, demanding to know who it is. There is no response but the noise grows louder.

The Doctor sinks into a chair, his face contorted in pain. He is under mental attack and he vows to fight.

Zoe is lost in the mist, completely directionless. She calls out for Jamie and the Doctor as she runs. At last she hears a response from Jamie and soon they are reunited. Both have realised that the Doctor was right. This is no mist-covered landscape. It is a void of opaque white nothingness. They decide to return to the TARDIS but they cannot tell which direction to go. Everything looks the same and they are well and truly lost.

Jamie tells Zoe of the Doctor's theory about the visions on the scanner. She wonders who would want to tempt them out and why. Jamie's not sure he wants to find out. They begin calling out for the Doctor. Hopefully he will hear them and guide them back.

In the TARDIS, the Doctor does hear them. However, he believes this is just another attempt to lure him out. He stays put, determined to fight the power being levelled against him.

Zoe and Jamie are losing hope. What's worse, Jamie's sure they're being watched. Unseen, a group of white robots does indeed observe them with blank-eyed gazes.

Staring into the mist, Zoe sees again the vision of her home city and she believes. Jamie does his best to remind her it's an illusion and eventually brings her back. She was being made to see what she most wanted to see. But just as she is freed, the same thing happens to Jamie. He is drawn again to the vision of Scotland. Zoe is forced to slap him to bring him back to reality. The Doctor was right about this place. They must try to return to the TARDIS.

As they turn to try again, they are surrounded by the white robots. They all have weapons mounted in their chests and appear very unfriendly indeed. Zoe screams.

The scream carries to the TARDIS where the Doctor hears it. However, he is also witnessing a vision of his companions, dressed all in white, beckoning to him. This he resists, but he cannot as easily ignore their distress. He continues to fight the mental battle and is finally addressed by his enemy. A disembodied voice urges him to follow his friends and save them.

The Doctor refuses to give in but the sinister voice says confidently that he will.

The robots open fire on Jamie and Zoe with some sort of disorientation ray. Zoe screams again.

The Doctor is still under attack by the voice which urges him out. He fights but also knows that he cannot abandon his companions. Of his own free will, he goes outside.

In the void, the Doctor can see nothing. However, he realises that his mind is powerful here and so he uses it - to see his companions and to summon them to him. They must concentrate on him and the TARDIS. They are the only real things here. This plan works and Jamie and Zoe walk slowly toward him. He is becoming desperate.

The white robots follow and start to open fire again. The Doctor leaps forward and shoves his companions inside.

They make it in, back to normal, and the Doctor closes the doors. As he starts the dematerialisation process, the Doctor tells them that they've been nowhere. All that they've experienced has been pure imagination. He stresses the danger they are now in, even though Jamie and Zoe are sure they're safe in the TARDIS.

A strange noise interrupts the dematerialisation process, worrying the Doctor, but it soon goes away. Feeling safe and quite worn out, Jamie sits down for a nap. He'll wake up when they arrive wherever.

Zoe apologises for going outside but the Doctor reassures her that she had little control. Whoever was tempting them was very strong indeed. It even worked on the Doctor.

The Doctor notices a power meter registering too low a number, meaning that the TARDIS is using more power than it's storing. He works to activate a power booster unit.

Meanwhile, Jamie is in the grip of a terrifying dream.

The Doctor activates the power booster but it is slow to respond. Shortly it begins to creep up, but a vibration begins issuing from all around them. Jamie awakes with a start and tries to explain his dream of a charging unicorn but Zoe shushes him. They see that the Doctor has backed away from the console and is holding a hand to his head. The vibration is alien and is growing stronger.

Jamie and Zoe can feel it now too, invading their minds. The Doctor calls to them to concentrate on the numbers on the meter but it is a losing battle. The noise grows louder and more insistent. The Doctor is forced away from the console and back to the wall, trying with all his strength to fight the attack.

The TARDIS begins spinning all around them. Outside, the ship spins slowly in a black void, winking in and out of vision. The vibration grows and suddenly the TARDIS splits apart, its pieces hurled into the void.

The console is left turning in the nothingness, Zoe and Jamie clinging to it as if to a life raft. Across the void, Zoe sees the Doctor. He spins in place, his eyes closed as if dead.

The TARDIS console spins away into the misty void.

Some time later, Jamie is alone in a dim and strangely-silent landscape - a forest of oddly-shaped trees bathed in darkness. He calls out for his friends and receives a distant reply from Zoe. He hurries forward, only to find his way blocked by an English Redcoat. He doesn't know where he is or why, but he does know the enemy when he sees him. The soldier is armed with a rifle and Jamie goes on the attack. He draws his dirk, shouts out the clan battle cry, and attacks.

The Redcoat turns and fires directly at Jamie. But instead of a bullet, the gun emits a puff of smoke and Jamie is frozen. Not just frozen, but stopped cold. Jamie has been reduced to a 2-dimensional cutout, arm raised high to attack. He is no longer a real person.

Elsewhere, Zoe continues to call out to Jamie, becoming worried when he doesn't reply. Suddenly, her way is blocked by the appearance of a heavy stone wall. Soon, she is surrounded. She is trapped. A heavy door appears in one wall and creaks open. With nowhere else to go, Zoe approaches. Inside is solid darkness, but it is her only avenue of movement, so she takes it.

But there is no floor beneath her feet. One step and she pitches forward with a scream.

In a futuristic control room, a shadowy figure monitors the fate of Jamie and Zoe. The man is pleased. Now for the Doctor... However, he is nowhere to be seen. The Doctor has eluded capture for the moment. The man seems to be of two distinct minds, some of his words silky and calm, others harsh and angry. The orders he gives are forceful, although it is not clear who or what is receiving them.

The Doctor must be found. All areas must be searched.

The Doctor sits unconscious in another part of the silent forest. He is worried about his friends and yet still fighting the power that was attacking his mind in the TARDIS as he thrashes toward consciousness. He wakes with a start, taking in the very strange landscape around him. He stands and calls out for his companions.

First Jamie, then Zoe call out to him. They are at least alive, that's good. He sets about trying to locate them but cannot at first. The task is made much more difficult when they both call at once. He silences them testily and then decides to go after Jamie, who sounds to be nearest. He follows Jamie's voice.

The shadowy man in the control room continues his search, but it is fruitless. He decides that some light may aid his searchers.

The Doctor is also having little luck finding Jamie, the darkness of the maze-like forest hampering his movement. Suddenly the area is flooded with light. He doesn't know where it came from but the Doctor is glad for it at the moment.

He becomes aware of a strange mechanical sound, accompanied by staccato footsteps. He hides in the curve of one of the trees and watches as a group of soldiers march into view. But they are not ordinary soldiers. They move with a mechanical gait, one after the other. They are very tall and their black hats contain lights. They scan the area for someone or something. He is reasonably certain that they are after him.

In the control room, everything "seen" by the soldiers is relayed on monitors. The Doctor does not appear on them and the man is angry. He orders the soldiers to continue searching. It is imperative that the Doctor be found.

The soldiers march on, their blocky boots leading them mercifully away from the Doctor's hiding place.

Wondering again what sort of world he's landed in, the Doctor starts to resume his search for Jamie. However, he's stopped by a very tall man in breaches and a tri-corne hat bellowing some foreign language at him. The man also carries a flintlock pistol, pointed at the Doctor. He puts his hands up and approaches.

After a few miscues, communication is established when the Doctor tries English. The man, a sailor or adventurer of some sort, is from England and seems pleased to make the Doctor's acquaintance. However, his friendliness seems to come and go rapidly as he translates his earlier words, accusing the Doctor of being a highwayman or a traitor. The Doctor learns that the man set sail from Bristol on May 4, 1699, and appears to be the only survivor of his ship. He knows not what happened to the others.

The Doctor, too, is alone and he tries to make a connection with the sailor, but that seems impossible as he thinks the Doctor is a traitor. When the Doctor explains that it is difficult to be a traitor in a land you know nothing about, the sailor at least puts his gun away, a great relief to the Doctor. Alas the sailor has seen nothing of Jamie or Zoe and is not permitted to aid the Doctor in his search by order of "the Master". This Master has "articles of impeachment" against the Doctor for treason. Very interesting.

And the sailor will not stay long. "To avoid suspicion," he decides to retire. The Doctor still has questions and tries to follow. He turns the corner where the man went and finds nothing! The sailor has vanished. Very odd indeed.

Shaking off his feeling of unease, the Doctor resumes his search for his friends. What he finds instead is a group of stern-looking children. They leap from nowhere and surround him, badgering him with riddles. Shaken, he answers their nonsense question, only to end up getting pinched. The Doctor starts to ask questions of the children, only to have a fake sword thrust under his chin by one of the boys. Another puzzle - "what can you make of a sword?". The clues lead him to the letters - S-W-O-R-D - which he rearranges to spell W-O-R-D-S. The sword turns into a dictionary.

Puzzled, the Doctor tries to ask the children what is happening. They only tell him he has "answered correctly" and "may be suitable" before racing off for tea. They, too, vanish suddenly like the sailor. This is all very odd and he has very little information to go on.

Jamie calls out to the Doctor from very nearby. Moving forward, he finds the 2-dimensional cutout. Surely this is just another trick. Behind him appear two objects - an old-fashioned safe and a wishing well. They appear to be real, but they are no help to him here in this strange world. Frustrated, he tosses the useless dictionary down the well...only to be greeted with a sinister laugh. Suddenly two visions appear. One is a thick mist, in which float the letter M & T, crossed through. The other is a picture of a hand bearing the letter H, also crossed through. The Doctor recognises another puzzle, this time a rebus.

Putting the clues together, he comes up with the solution: "Jamie is safe and well". With that, the cut-out changes and Jamie no longer has a face. On a board next to him is a selection of eyes, noses, and mouths from which the Doctor must reconstruct the face. With great confidence, he does so - only to get it wrong!

Jamie comes back to 3-dimensional life but he is not himself. His face is completely different even though he insists he is still the same person. Another sinister laugh tells the Doctor that this is a trick played by the person who brought them here. Jamie is shocked to see his new face but seems willing to accept it for the moment. When he recalls what happened to them in the TARDIS - including his dream about the charging unicorn - Jamie convinces the Doctor of his identity. The Doctor is horrified to learn that the TARDIS broke up.

A muffled call from Zoe galvanizes them into action. They hurry toward the sound and fun into a brick wall. She must be behind it. However, the "door" isn't really a door at all, it's just painted on the wall. Another riddle. Q: When is a door not a door? A: When it's ajar. Suddenly the wall fade, revealing a giant jar with Zoe trapped inside.

Jamie and the Doctor have a good laugh over her predicament before pulling the indignant girl from the jar. She is ready to complain further but stops at the sight of Jamie's new face. The Doctor promises to explain later but first they'd all like to get out of this weird wood. He sends Jamie along to explore whilst he and Zoe quietly discuss the "change" in their friend. Zoe thinks such a thing impossible, but the Doctor fears they may be in a place where nothing is impossible.

After some time, the threesome has come no closer to escape, even after walking for miles. Zoe sits for a rest whilst Jamie suggests climbing one of the trees in order to get a better view. Doing so only results in deepening the mystery. This "tree" isn't a tree at all - it's a giant letter! S. And each oddly-shaped tree is another letter. They are in a forest of words, spelling out English aphorisms and sayings. The Doctor surmises they must be in a world of words.

Luckily, Jamie spies a way out of the forest and he climbs down. The group doesn't get far before they are confronted by the sailor. Zoe is worried but the Doctor seems confident that the man is a friend. When first they met, the man's responses to the Doctor seemed somewhat odd. But this time, as they speak of escape, they are downright dissonant. The words seem to address the previous comment but also seem to have been lifted from some other context. They don't quite fit.

They do learn that the "tests" which they have been set are the work of this mysterious Master and are something to do with "a course of study" which is required prior to service in this land. The Doctor inquires about the army of robotic soldiers he saw earlier but the sailor denies any knowledge. When their mechanical noise fills the air, the Doctor and his friends hide in amongst the letters but the sailor stays put as he senses no danger.

The soldiers arrive and surround the man. Inexplicably, he calls out to the Doctor and his friends, revealing their hiding places to the soldiers.

In the control room, the shadowy Master is pleased. All of the fugitives are now in his power. They are to be led away.

Jamie is furious at the soldier for his betrayal but the Doctor explains that he can't see them. To him they don't exist. The sailor bids them a pleasant goodbye and disappears.

The soldiers begin to herd their prisoners in the other direction. Zoe notes that these are not really robots at all, but toy soldiers. All have wind-up keys in their backs and walk with the stiff gait of clockwork toys. Particularly nasty toys, notes the Doctor.

The prisoners are herded out of the forest in to a completely blackened, open area. Then suddenly the soldiers are gone and the travellers are very much alone.

To the Master, it is mission accomplished.

Jamie is very uneasy. He feels that he's been here before. A distant thundering sound fills the air - a galloping horse. It grows louder and nearer and soon they see the source - not a horse but a gleaming white unicorn. It is Jamie's nightmare come true.

Jamie and Zoe are ready to run - anywhere in order to escape the charging unicorn. Amazingly, the Doctor orders them to hold their ground, going so far as to hold them still. He also reminds them that unicorns are mythical. They do not exist. However, they can see it clearly and cannot accept this. The Doctor repeats his order, even more firmly, telling them to say it out loud: "the unicorn doesn't exist."

They do so and to their amazement, the unicorn freezes in space mere feet from them. It is now just a two-dimensional picture, clearly unreal. Jamie and Zoe cannot understand what's happened. The Doctor explains this is another "test" set by the mysterious "Master". As long as Jamie and Zoe believed in it, the unicorn was real - and dangerous. Their belief was affecting his disbelief. They weren't safe until Jamie and Zoe reinforced their disbelief out loud.

Jamie cannot understand who could have thought up something like this. The Doctor wonders as well, but knows it must be someone with a fantastic mind.

In his control room, the shadowy Master overhears this and accepts the complement. He returns it, speaking out loud but to no one in particular. He is impressed at the speed with which the Doctor is learning the "rules" in this world. He says that "we were right" to choose him.

The Doctor and his friends are set upon by clockwork soldiers who start to close in. They back away into the dark void but the Master orders his soldiers not to follow. The three cannot escape their destiny. The trap is set for them. He is content to wait until they walk into it.

The Doctor, Jamie, and Zoe find themselves in a thicket of cobwebs. Jamie leads the way, chopping at them with his dirk. It seems to go on forever but at least they've left the soldiers behind. At last they come to a house. Jamie starts toward it only to spy the Redcoat he tangled with earlier. He raises his dirk, gives the battle cry, and attacks. As before, the Redcoat fires directly at Jamie's face. In a puff of smoke, Jamie is once again reduced to a faceless cardboard cutout and the soldier vanishes.

Zoe and the Doctor run to him. She is horrified by the blank face but the Doctor is unfazed. He waits impatiently for the puzzle. A board appears with various face parts and all is clear to Zoe. This has happened before and the Doctor got it wrong! That is why Jamie's face changed. Stung by the accusation, the Doctor says he was rushed before. He is confident as he starts again.

Zoe watches over the Doctor carefully as he works, correcting his errors. Before long, the last piece is in place and Jamie comes back to life again, looking like his old self. The Doctor hands him the mirror and all are pleased at the result.

Jamie is eager to continue on to investigate the house. The squeaky door leads into an entry seemingly carved from solid rock. Cobwebs are everywhere and candles are alight. Someone's been here recently it seems. There are four tunnels leading off the entry, dark and featureless. The Doctor spies a ball of twine and immediately recognises it as the "classic" way of getting through a maze. He has Jamie tie one end to the door.

He finds that the door is locked and so they must investigate the tunnels. The string will keep them from getting lost, but it will also lead any pursuers straight to them. This is a risk they must take. The Doctor picks a tunnel and leads the way. Dripping water and a hum like a resonant human voice are the only sounds around them.

The Master watches on a map as three points of light move along a maze. The Doctor and his friends. Through a series of twists and turns, the correct path leads to the centre, a chamber which looks much like a human heart. How long will it take them to reach it?

The Doctor and Zoe lead on, with Jamie unrolling the twine as they go. They have been travelling for some time. At yet another junction, Zoe confidently decides they should go to the right. She has been doing calculation in her head and thinks the maze in constructed on a logical arithmetic progression. Right is the way to go. The Doctor is unsure and hesitates. On top of this, the string has run out. Jamie's all for going back but the Doctor isn't ready to stop just yet.

Jamie is left on guard whilst the Doctor and Zoe investigate the right fork. Zoe's sure this is the right way, but is it the way out or just deeper in? Jamie is left behind, whistling to calm his nerves.

The Mater, in his more sinister tones, urges the two blips on his screen to hurry on. They are so near the heart of the maze now!

The Doctor and Zoe reach the central chamber. As she predicted, it is not a way out, simply a central point with many tunnels leading off. The Doctor is expecting a welcoming party and seems somewhat disappointed that there is no one. However, something has been here. They find a heap of bones on the ground, well-gnawed, as well as the tracks of some strange beast. It is horrible.

They are startled by the roar of some kind of beast, very nearby. Zoe clings to the Doctor as she repeats the story of the minotaur in the labyrinth. It all adds up. A second roar and soon the creature is upon them. A giant creature half-man, half-bull. The Doctor starts to deny the creature's existence when Zoe cries out. It continues to approach.

Jamie hears the cry and the roars and abandons his post to go and help his friends. However, he is chased away by a toy soldier. The soldier corners him but Jamie is quick to spot a way out. Realising that the soldier "sees" by means of the light in its tall hat, Jamie removes his vest and covers the light. The soldier is now blind and Jamie is free to escape.

The Master is livid when he observes this and orders the soldier to free itself and pursue Jamie.

Zoe is having a difficult time suspending her belief in the minotaur as it is clearly there in front of her. It moves in for the kill, the Doctor shouting desperately for her to deny its existence. At last she does so and the creatures vanishes. Its roar cuts off abruptly and they are save. Relieved, they head back to find Jamie.

However, Jamie is not at the junction where they left him. Zoe finds his vest and becomes worried. She calls out and there is movement nearby. It is not Jamie who emerges from the shadows, but the enigmatic adventurer who gave them away earlier. In his typically oblique speech, he says he has not seen the missing Jamie.

In response to a question from the Doctor, the man says he has met the Master and seen his "palace", a citadel high on a hill. From the wording of this response, the Doctor seems to glean an important insight into the man. When he starts to answer a question about his background, the Doctor actually finishes his sentence for him. He knows who the adventurer is: Lemuel Gulliver! The Doctor is pleased and hopes to chat with him soon, but not just now. Equally pleased, Gulliver takes his leave for now, disappearing into the tunnels.

The Doctor explains to Zoe that this world they've tumbled into is a place where fictional characters are alive: the minotaur, unicorns, and Gulliver. They're all real here. Gulliver spoke in his odd fashion because he could only speak the words that his creator Jonathan Swift gave him in the book. Zoe finds it all ridiculous but it is clearly true. The only question that remains is why they were brought here. The Doctor is uncertain of this as yet, but he seems worried. They head off to try and find Jamie.

Jamie's flight from the toy soldier has led him outside, to the base of a cliff. The soldier is right behind him so Jamie does the only think he can, scrambling up the cliff barehanded as far as he can. The soldier is left far behind, but Jamie is soon stuck on a ledge half way up. He can't go back, nor can he go on without a rope to aid him.

To his astonishment, a rope falls from atop the cliff to land in his hands. It appears to be well-tethered at the top and he wastes no time in climbing. The soldier wanders off whilst Jamie continues his strenuous ascent.

The odd rope terminates inside the window of a castle tower. Jamie reaches the base of the tower but can go no further. All that is left to him is the window. He tries to gather the rope but his tug elicits a squeak of protest from inside. A petite blonde girl appears, taking Jamie to task. It turns out that the "rope" is her hair; she doesn't mind him climbing in - she's quite used to that - but the tugging really does hurt. She introduces herself as the Princess Rapunzel!

She is quite disappointed to learn that Jamie is neither a prince nor a woodcutter's son and she doesn't think that it would be allowed for a piper's son to enter through her window. Jamie turns on the charm, explaining that he has little alternative but to come in. Heaving a sigh of regret at Jamie's lack of royal heritage, she agrees to let the young man in.

When he gets inside, Jamie finds no sign of Rapunzel. She has vanished. He sees he is not in a princess' chamber but is actually inside some sort of futuristic control room with screens and banks of instruments. A large circular monitor comes to life displaying the frontispiece of a book. He accidentally activates a recording machine which begins playing an audio version of Little Women. Jamie quickly turns it off.

He is drawn to several lighted panels on one wall. Suddenly they begin flashing and an old-fashioned ticker tape machine clatters to life. Jamie reads off the words printed there with growing concern. It says that the Doctor and Zoe have given up their fruitless search for Jamie and have returned to the cave. There, a new terror awaits them!

This is in fact what is happening. Back in the cave, the Doctor and Zoe notice a statue in one corner that was not there before. It is clearly made of stone but suddenly comes to life. The statue is that of a woman with snakes for hair. The snakes hiss to life, writhing on her head. Medusa!

In the control room, Jamie reads this on the ticker tape. It sounds like a story - a narrative. It is almost as if someone is summarising the Doctor and Zoe's adventure! Jamie reads about Medusa and the fact that one glance from her eyes will turn his friends to stone.

Zoe and the Doctor have turned away but can see from the shadows that Medusa is coming toward them. The Doctor urges Zoe to deny the creature's existence but she is too frightened to think clearly. The Doctor becomes worried as Medusa's hand reaches out toward them. If Zoe cannot suspend her disbelief, Medusa can turn them both to stone.

Zoe cannot shake her belief in Medusa, not with the icy cold fingers on her face, trying to turn her eyes. The Doctor cannot get through to her.

In the control room, Jamie continues reading the ticker tape describing what is happening to his friends in terms of an adventure story. However, the story takes a turn as he reads about the Doctor finding a sword and slaying Medusa. Jamie can hardly believe this. The Doctor would never do such a thing, would he?

Indeed the Doctor does find a sword at his feet and for a moment he considers slaying Medusa to end the nightmare. He is egged on by a terrified Zoe. However, he realises he can't kill a fictional character, well-known myth or not, and he drops the sword. Remembering more of the myth, he produces his mirror and, like Perseus, looks at Medusa's reflection.

Zoe does so as well and her fear subsides. Robbed of her power against them, Medusa reverts to a statue. The snakes stop writhing and hissing and all is quiet again. Zoe and the Doctor are safe.

In the control room, Jamie reads the finale in a much different way: "Cancel. Cancel. Cancel. The Doctor test results - failure." The machine falls silent. Not comprehending and not wishing to stick around any longer, Jamie leaves the ticker tape and heads for the door. On the threshold, however, he trips a light beam and an alarm goes off. A grille slides over the window and Jamie is trapped. A call goes out ordering a search for the intruder.

Into the room strides Gulliver. Jamie is certain he has been sent to capture him but the man makes no move. In his inimitable way, he says he's been looking for Jamie at the behest of his friends. He assures Jamie that the Doctor and Zoe are safe and well. Jamie hears an eerily familiar sound and ducks out of sight. The true search party approaches.

A secret door gives way behind him and Jamie finds a cupboard in which to hide. He closes the door, begging Gulliver not to give him away. Three white robots appear in the doorway and execute a search. Clearly the Master is getting serious; toy soldiers are no longer enough. They find nothing and move on. Gulliver stands idly bay, waiting with his sword and pistol drawn to defend Jamie against his pursuers. He has no reaction at all to the robots.

Jamie emerges and he is safe. Gulliver reports seeing no one about but Jamie doesn't want to stand around and figure it out. He tries the grille on the window but it won't budge. Gulliver - slow on the uptake - at last realises that Jamie is trying to gain his liberty. This, he says, is all together impossible.

Zoe and the Doctor stand at the base of the cliff, looking up at the massive towers of the citadel. It is where they must go, but they are at a loss as to how to reach it. Suddenly an energy burst crackles through the air and slams into the rock wall. The Doctor and Zoe duck just in time. With a dramatic flash of coloured light, an unlikely figure appears before them. Some sort of costumed superhero with an impossibly-sculpted body, a cowl, and a short cape. He carries a sinister-looking ray gun and orders Zoe and the Doctor to put their hands up in a bad German accent.

Zoe identifies him as the Karkus, another fictional character. The Doctor is sceptical of him, especially the gun. Zoe calls it an anti-molecular ray disintegrator and the Doctor scoffs. Such a weapon is scientifically impossible. Suddenly the gun disappears. The short-tempered Karkus is livid. He vows to tear the Doctor apart with his bare hands.

Zoe urges the Doctor to say out loud that the Karkus doesn't exist - to deny him reality in this world - however the Doctor has never heard of him and can't truly say he is fiction. This allows the Karkus to stay here and to attack the Doctor with his "superhuman strength". The Doctor dodges out of the way as the Karkus dives for him. Zoe isn't so quick and gets caught in the fight. But Zoe is not his target; the Karkus is after the Doctor.

To save her friend, Zoe joins the fray. Amazingly, she is able to defeat the Karkus with ease, using some heretofore unrevealed judo skills. She flips and throws the giant and finally gets him into a chokehold. The "mighty" Karkus submits like a frightened little mouse and he is now Zoe's servant. He agrees to lead them to the citadel.

Zoe explains to the Doctor that the Karkus is a strip cartoon character from the "Hourly Telepress", very popular in the year 2000. The Doctor searches his memory and finally recalls him, although he notes that he was very busy when he was in 2000 and didn't have much time to follow the strip cartoons. Zoe urges him to "follow the Karkus" quickly now as he's already halfway up the cliff!

Shortly they are at the main door, which is firmly closed. Zoe sends the Karkus away, although the Doctor keeps his cape as a souvenir. He then boldly rings the bell to be admitted. But it's not as simple as that. He must pretend to be the Karkus, using the voice and fictional source before they can be admitted. Fortunately, it is a voice-only system and the Doctor's impersonation passes muster. The door opens and they hurry in.

Jamie, still looking for an exit, is trying to reason with Gulliver. The adventurer assures him he saw no robots but will agree that Jamie was hiding from some search party. He thinks it's the Yahoos! Jamie can only register his disbelief. However he is shortly gladdened when Zoe and the Doctor appear at the door. Jamie hurries over to stop them entering and setting off the alarm.

As the Doctor inspects the light beam, Jamie tells them of the reappearance of the white robots. The Doctor is not surprised; he though they'd turn up again at some point. The Doctor lifts Zoe over the light beam and he himself jumps over. They are in safely. Jamie explains how he got here and hopes the Doctor can find a way out. To his horror, the Doctor insists on staying. He is determined to meet this Master.

Gulliver tries to warn him off this course, noting the Master's stringent rules. The implication is that the Doctor and his friends have breached them and will be punished. He suggests that they make peace with the Master and settle down here in this world. Again, there is an implication that they will not be able to get away even if they want to. The Doctor says he'll think it over, humouring Gulliver, and the adventurer takes his leave.

Of course the Doctor has no intention of giving in. They're staying on and fighting on. Zoe mentions their tussle with Medusa and Jamie shows them the ticker tape machine on which he read about it. Some things become clearer to the Doctor. When someone writes about events after they happen, that's history. When the writing comes first, that's fiction. If he and Zoe had done as was written on the tape, they would have become fiction!

Horrified, Zoe is resolved to get out of here. She storms through the doorway, forgetting completely about the alarm system. The alarm goes off and Jamie and Zoe scramble for someplace to hide. The Doctor, however, stays put. He is ready to meet the Master and supposes that this is the fastest way. Soon, three white robots arrive and move silently toward the prisoners. The Doctor begins to worry that perhaps he won't live long enough to meet the Master.

He, Jamie, and Zoe back away and suddenly a section of wall slides away, revealing a black void. The Master's sinister voice invites them in with barely-disguised menace. The invitation is not a suggestion. The robots move forward to force them in and the wall slides shut behind.

A moment later, they find are admitted into what appears to be a command centre. It seems to float in blackness, lit by isolated pools of light. There are more robots in attendance. At the centre is a giant glowing orb, angular and transparent. Inside, there appears to be a mix of electronic circuits and living matter. It looks like what it is - an enormous brain, rotating on a support.

Just below the brain is a desk. Behind it sits the Master. For all his sinister words and machinations, he is really quite an ordinary-looking man. He is rather old with wispy hair and an unkempt beard. He wears an old suit with a waistcoat and tie, along with fingerless gloves. He wears tiny glasses and a small skull-cap on his head. To the cap is attached a crown of wires which trail down his back. In any ordinary circumstances, he would appear to be just a harmless old man, albeit rather antiquated. The Doctor and his friends know better.

The Master speaks quite chattily about the enormous responsibility his position entails. But, he says, it is very rewarding. The Doctor takes the notion of "responsibility" a bit further and learns that the Master is in the service of a higher power, one of great intellect and scope. He congratulates the Doctor on the skill with which he passed the stages of his "examination". He does not explain why the Doctor was brought here, he only tells the story of how he ended up here after dozing off over his desk in the summer of 1926. It seems so long ago now...

The Master explains that he was the writer of an adventure serial for boys in the Ensign magazine. He produced 5,000 words per week for 25 years; surely some sort of record! That is why he as chosen to work here. He appears to be in charge of this world of fiction, but the Doctor surmises that this place is firmly in charge of him. The Master says that his creative energy keeps the whole world going. The Doctor thinks this a particularly cruel form of slavery, though the Master refutes that.

Suddenly, the brain comes to life with lights and sound. The Master freezes as if receiving instructions and begins writing in his ledger with pen and ink. Jamie and Zoe wish to use the distraction to mount an escape but the Doctor wishes to stay. He must learn more about this place. As the Master returns to himself, Zoe and Jamie decide to sidle off and try to find an escape route. The Doctor engages the Master's attention, learning that this world contains a library of all known works of fiction ever produced on Earth.

Behind the Master Brain, Jamie and Zoe find themselves in an enormous library of all these works. Dusty volumes litter the floor and fill every shelf as far as the eye can see. The shelves themselves form a sort of maze through which Jamie and Zoe must navigate.

The Master explains that the creative genius of humans is far above any other creature and gives them a unique role here. All that is needed is one man with a boundless imagination to serve as a "powerhouse" for the intelligence that he serves. And that is why the Doctor was brought here. The Master is no longer young and the nearly ageless Doctor has been chosen to take over for him. The Doctor adamantly refuses and the brain goes into overdrive. The Master's face contorts to a scowl and his voice turns gruff and staccato. Refusal is unacceptable. The Doctor will submit.

Jamie and Zoe are lost in the mast of shelves and are soon surrounded by white robots. They try to escape, taking the only open route.

The Master announces that the Doctor has no alternative but to submit, despite his refusal. The Master seems very sure and soon reveals why. He reads the latest story he is writing - the capture of Jamie and Zoe. He urges the Doctor to give in for their sake. Torn between he friends' lives and the larger evil at work, the Doctor hesitates. The Master directs him to a monitor overhead.

They watch as Jamie and Zoe are inundated by the disorienting rays from the white robots. They stagger backward clutching their heads. They find themselves in between the pages of an enormous book, trapped and unable to get out. The covers of the book begin to move forward, squeezing Jamie and Zoe between them.

The Doctor is horrified when the Master tells him Zoe and Jamie are now no longer human beings. They have been turned into fiction! If the Doctor consents to take his place, he can release them as his first official act. The Doctor, however, steadfastly refuses. He is certain there is some other way.

His patience nearing an end, the Master calls in a group of white robots to capture the Doctor and force him to submit. The nimble Doctor dodges away from them and heads for one of the very tall bookcases around the control area. Using the shelves as rungs, he climbs the bookcase and disappears upward. The Master is content to play this game a little longer, certain that he now has the ammunition he needs to bring the Doctor under his power.

The Doctor's climb takes him to the roof of the citadel. In the silence he hears footsteps and hides. He is very surprised indeed to see Jamie and Zoe, looking real and solid and human. However, when they continue to repeat the same few sentences over and over, the Doctor realises that they are merely characters being manipulated by the Master.

The Doctor spies a skylight leading down into a room which contains a very large typewriter. He believes it is the master tape, collecting all the fiction which powers this world. Perhaps, if he could get down there and create some fiction of his own... However, the skylight won't budge. He would need the strength of the Karkus to open it. Instantly, the mighty character appears in a blaze of light and easily tears open the casement to the skylight. The drop into the room is very far and the Doctor needs a rope. The Karkus goes to fetch one.

While he waits, the Doctor addresses the fictional versions of his companions, hoping somehow to reach the real ones through them. If only they could resist the control of the Master. But it is no use.

The Karkus returns with the Princess Rapunzel. She gladly consents to let the Doctor climb her hair, even though he's not a prince. The Karkus uses his mighty arm to anchor the rope and down the Doctor goes. He seats himself at the typewriter and prepares to write.

The Master observes him on a monitor gleefully. This has worked out much better than he'd hoped. He urges the Doctor to complete his task.

The Doctor is about to type a sentence that ends this whole business, showing him vanquishing the enemy, but he stops himself when he realises that is exactly what he was meant to do. If he writes about himself, then he becomes fiction! An ingenious trap.

Looking over, the Doctor notices the toy soldier sitting quietly in a corner, the light in its hat trained on him. He knows he is being observed and hurries out of the room, scrambling up Rapunzel's hair.

The Master is furious and his patience is at an end. He will finish this game once and for all.

The Doctor is worried when he finds Jamie and Zoe are missing from the roof. He calls to them but it is Gulliver and the children he met earlier who join him. The children pelt him with chatter and questions, disrupting his vital concentration.

Scribbling in his journal, the Master creates a scenario in which Jamie and Zoe realise the Doctor is the most monstrous villain in creation. There is no punishment severe enough for his crimes. When the two characters are brought before him, they repeat his words perfectly. They await instructions on how to deal with the villainous Doctor.

The Doctor sits deep in thought on the roof whilst the children play Ring Around the Rosie. They and Gulliver approach him, perhaps to help, perhaps to further distract him. The children suddenly notice something unusual appear and point it out. The Doctor is amazed to see the TARDIS safe and sound and in one piece. Jamie and Zoe, seeming like their old selves, emerge from it eager to get him inside and be on their way. Caught up in their enthusiasm, the Doctor goes in.

But Jamie and Zoe don't follow. They close the door behind him, laughing evilly. They have trapped their enemy as instructed. The front of the false TARDIS falls away, revealing the Doctor now trapped in a Perspex box. The children crowd around and jeer at him as the box, Doctor and all, fades away.

The Master is pleased that his characters performed so perfectly. The Doctor arrives in the master control area, still locked in to the machinery. A helmet is fitted over his head and the Master reveals that he has been incorporated into the computer itself. It turns out that his brain is needed for another purpose. Running this world is not all that he is called for. In fact, the plan is to take over Earth. All the humans will be removed from the planet and brought here as fiction, leaving the Earth undamaged and uninhabited for the purposes of the master brain.

However, the Doctor quickly realises that this plan has a flaw. He himself is now incorporated into the master brain, just as the Master is. The computer will now create whatever fiction he imagines! The Master is horrified. This is against all the rules and he hopes the Doctor is wrong and that it is the computer who is in control. The Doctor very much doubts it. He has been given equal power to the Master. It is now a battle of wits between them, a battle the Doctor intends to win.

Concentrating, the Doctor calls out to Jamie and Zoe - the real ones - and urges them to fight the power holding them. He urges them to open the book and escape. An alarm issues from the master brain as it realises the Doctor may succeed. The Master summons all the white robots to protect the computer brain.

The Doctor urges his companions to forget fiction and hold on to real life.

One the roof, the fictional Jamie and Zoe disappear, much to the sadness of their fellow characters. The real ones respond to the Doctor's call and push harder against the pages of the book. With a final effort, they are free. They vanish from the library and reappear on the roof, the last place their characters were. The Master calls out a group of toy soldiers to seek them out and destroy them.

Jamie and Zoe are disorientated finding themselves on the roof and they get no help from Gulliver and the other characters. The soldiers are now closing in.

Using his new power, the Doctor summons the Karkus to defend them. At his bidding, the superhero uses his anti-molecular ray disintegrator to destroy the soldiers. Picking up the story, though, the Master has the Karkus turn the gun on his real enemies, Jamie and Zoe. The Doctor, however, adds a sentence that renders the gun empty and useless.

What follows is a bizarre game of "finish the story". The Master summons swordsman Cyrano de Bergerac to battle Jamie and Zoe whilst the Doctor summons D'Artagnan to fight him. When this produces a stalemate, the Master substitutes Blackbeard the pirate with his cutlass. The Doctor counters with Sir Lancelot in full armour and on horseback. The battle rages; and in the chaos, Jamie and Zoe escape down the skylight with the aid of Rapunzel's hair. They head off into the depths of the citadel, trying to find their way back to the Doctor.

An alarm sounds again from the master brain and it announces that the Doctor is now expendable. The chaos he has created is too much and must be ended. The Master is horrified. Without the Doctor there is no one to take over for him. He can't go on any longer, he says, his voice taking on a pleading tone. The master brain will not be swayed. It is in danger of overloading and is acting on self-preservation. The Doctor must be destroyed. Most surreally, the master brain speaks through the Master himself. In two different voices, he condemns the Doctor and tries to prevent it. But the master brain is firmly in control and the white robots arrive to carry out its orders.

The creatures' weapons are changed from the disorienting beams to destructor beams as they advance upon the Doctor. He tries to write his way out of the situation, but nearly falls into the trap of fictionalising himself. He realises that he cannot save himself. The robots drag him from the machine.

Meanwhile, Jamie and Zoe have found their way back down to master control. They crouch down behind the master brain and struggle for a plan to save the Doctor. Zoe has overheard the master brain express concern about overloading and she thinks she's got an idea. The Doctor is brought before the Master and the order is given to disintegrate. The robots turn to fire.

Zoe races into action, pressing every button on the control panels behind the master brain. Jamie joins in and alarms go off everywhere. The giant master brain pulses wildly and rotates faster. The robots freeze in place and the Doctor is safe for the moment. The Master calls out to stop them overloading the computer. The robots are ordered to open fire on Jamie and Zoe.

The Doctor leaps forward and snatches the crown of wires off the Master's head, releasing him from computer control. He groans and slumps forward. The Doctor hustles him away from ground zero.

Jamie drags Zoe away as the robots turn and fire. Their weapons are aimed directly at the computer control panels and soon they are exploding left and right. The Doctor stays hidden as the conflagration rages. Soon the entirety of master control is ablaze and smoke fills the air.

Jamie and Zoe join the Doctor and together they drag the Master away from the conflagration. They find themselves in a black void. The Master, now just an ordinary old man, has regained himself somewhat but is unclear as to where he is or what's happening. The Doctor says only that he was kidnapped, just as they all were.

The Doctor hopes that the white robots will completely destroy the master brain and each other. If so, this world will collapse completely. Zoe worries about Gulliver and the others but the Doctor reminds her that they are fiction. They cannot be killed. As they speak, they are enveloped in an ever-thickening mist. The Doctor hopes that with the destruction of this world, they will all be returned to reality. However, they could just as easily be hurled into oblivion.

Either way, they will soon find out. The mist enshrouds them completely as this fictional world dies. They all vanish within it.

The Doctor is right. As reality takes them back, the old man is returned to Earth - with another fantastic story to tell - and the TARDIS reforms itself in space. Its crew is back aboard and headed to their next adventure.