The TARDIS arrives in a white void, having made an emergency take-off to escape the volcanic eruption on Dulkis. The Doctor, Jamie and Zoe find themselves in the Land of Fiction, where characters from the imagination come to life, and The Master, the mysterious ruler, chooses the Doctor to take his place.

With the TARDIS destroyed, the Doctor, Jamie and Zoe find themselves in a strange forest patrolled by mysterious soldiers.

The Doctor realises that the travellers are trapped in a world where fiction is real and where creatures are a threat if people believe in them.

The Doctor, Jamie and Zoe reach the citadel at the centre of the land, where they finally encounter the Master of the Land of Fiction.

With Jamie and Zoe having been turned into fiction, the Doctor must find a way to save them without suffering the same fate or becoming part of the Master Brain.