Second Doctor, 1968, story 56, The Mind Robber.
EPISODE 1
The TARDIS is buried in lava after a volcanic eruption on Dulkis, blowing the fluid links. The Doctor employs an emergency unit. It moves the TARDIS out of normal time and space, out of reality itself. They arrive in an endless White Void. While the Doctor fixes the TARDIS, Jamie and Zoe are lured outside. They are confronted by White Robots. The Doctor gets them back inside but, as they try to return to reality, the TARDIS explodes and the travellers are scattered into nothingness.
EPISODE 2
The TARDIS crew find themselves separated in a forest where the trees become letters when seen from above. The Doctor, after facing a series of riddles, finds Jamie as a cardboard cut-out with a blank face. When the Doctor selects facial components to reconstruct the face, he gets it wrong and Jamie returns to normal, looking nothing like he did before. The pair are reunited with Zoe. As the three try to figure out what has happened and where they are, they meet the fictional character Lemuel Gulliver, who gives them away to life-sized toy clockwork soldiers which he can't see. They are taken to the edge of the forest, where a unicorn charges at them.
EPISODE 3
The TARDIS crew turn turn the unicorn into a statue by loudly declaring, "It doesn't exist". They walk on and reach a house, where the Doctor is tasked with the Jamie face puzzle again. This time he gets it right and Jamie returns to normal. They discover that the house is the entrance to a labyrinth. The Doctor and Zoe leave Jamie behind. They encounter the Minotaur. Jamie, pursued by a soldier, climbs up a rock face with the help of Rapunzel's hair and enters a citadel through a window. He finds a series of computer banks which show a readout on the Doctor and Zoe's encounter with Medusa. Zoe cannot resist the urge to look at Medusa, though to do so will turn her to stone.
EPISODE 4
As the Doctor and Zoe avoid looking at Medusa, Jamie sees a readout describing how the Doctor slew the monster with a sword. Such a sword appears at the Doctor's side, but he refuses to use it because Medusa does not exist. He uses a mirror, turning Medusa to stone. The computer gives a failure reading, though Jamie does not know what it means. He continues to explore the citadel.
The Doctor and Zoe exit the labyrinth and encounter the Karkus, a cartoon character from the year 2000. The Doctor accidentally dispels the Karkus' anti-molecular ray disintegrator by commenting that no such weapon exists. The Karkus attacks them. The Doctor can't get rid of the Karkus, because he has never heard of the character before and cannot say for certain that the Karkus is not real. Zoe, however, beats the Karkus into submission with her martial arts skills and he allies with them. He takes them to the citadel, where they find Jamie. Zoe accidentally sets off an alarm, but they do not hide and let the White Robots take them to the main control room. Here, they meet the Master, a kidnapped Earth writer who underwent the same tests as they when he first arrived. He explains he is getting old and needs the Doctor to replace him as the creative source for the Land of Fiction. The Doctor refuses. While he is talking, Jamie and Zoe sneak out into a library where they encounter the White Robots again and are trapped in a giant book.
EPISODE 5
The Doctor refuses the Master's offer and escapes through a skylight. The Master hypnotises Jamie and Zoe. He gets them to trap the Doctor and links him to the Master Brain. The two battle, summoning a multitude of fictional characters to fight each other. The Doctor is careful not to explicitly reference himself or his companions in a fictional manner, less they then become fiction. The Doctor prevails in the battle. He releases Jamie and Zoe, who override the Master Brain, causing the White Robots to destroy each other.
The Doctor unplugs the Master from the Brain and they all retreat to a side room. The White Robots destroy the Master Brain, the TARDIS reassembles itself and normality is restored.
