Written by Peter Ling
Directed by David Maloney
To escape from the volcanic eruption on Dulkis, the Doctor uses an emergency unit which moves the TARDIS out of normal time and space. Subsequently, the travelers find themselves in an endless void, where they are menaced by White Robots while their minds are assaulted by an unseen force.
After successfully rescuing Jamie and Zoë from the void’s sinister influence, the Doctor returns them to the safety of the TARDIS. Suddenly, the TARDIS inexplicably explodes! They find themselves in a land of fiction, where they are hunted by life-size clockwork soldiers and encounter characters like Rapunzel and Swift's Lemuel Gulliver while navigating a forest of words.
This domain is presided over by a man known as the Master, a prolific English writer from 1926, who in turn is controlled by a Master Brain computer. The Master is desperate to escape his life of storytelling for his captors and wants the Doctor to take his place, while the Master Brain plots to take over the Earth.
The Doctor engages the Master in a battle of wills, fighting through the use of a variety of fictional characters. Zoë and Jamie meanwhile succeed in overloading the Master Brain and, in the confusion the White Robots destroy the computer, finally freeing the Master.
After spending most of last season telling straight-forward action-based monster stories, along comes The Mind Robber, one of the most whimsical, imaginative and enjoyable stories of the Troughton era. After a script problem found The Dominators reduced from six episodes to five, script editor Derrick Sherwin was forced to come up with an extra episode for this story, and he penned the brilliant and bizarre first episode, which features some of the most memorable imagery in the series' history. It's an incredible example of what the series could do with literally no budget. Sherwin could only use the contracted regulars, existing sets, and robots borrowed from another series. The result sets the tone for the rest of the story brilliantly, even if it really has little to do with the story that follows.
As for the story that follows, Peter Ling delivers scripts that are perfectly of their time while also evoking the more experimental style of the Hartnell era. This would be the last time the series would deliberately try to tell such a fantastic story for some time. Indeed, this story may the closest Doctor Who ever got to an out and out fantasy story, with Ling's use of mythical beasts, word games and evocative imagery combining to create a story that works even if it is almost totally unlike any other story of the era. The scripts are strange without being at all confusing, even the bizarre first episode, which makes them feel accessible and sophisticated at once. Troughton and the rest of the cast all are superb, clearly energized by the change in pace, and the loss of Frazer Hines to chicken pox results in one of the best sequences in the story, as the Doctor is forced to resemble Jamie's face, does it wrong, and allows Hamish Wilson to take over.
The story is directed by David Maloney, in his first outing with the series. He would become among the best directors the series ever had, and his talent and ingenuity combine to give the story pace and jeopardy, with a solid grasp of creating imagery and sequences that are strange and threatening without sacrificing the fantasy tone of the scripts. It's a remarkably strong debut.
For much of the rest of its life, Doctor Who would stick to monsters and aliens and invasions. But with its solid structure, great imagery and unusual tone, The Mind Robber remains one of the most fanciful, if among the most atypical stories in the series' history. It's also one of the very best of the Troughton era.