So what's the score? At the end of the previous story The Dominators the TARDIS is stuck in lava from a volcanic eruption... Of course, the Doctor panics and hits a switch on the TARDIS console and the travellers are transported out of time and space to a void where an alien intelligence has made a fantasy world out of people's imaginations. Episode 1 stands out on it's own as a masterpiece, even though it was rushed together by the production team because there wasn't enough in the script to pad out over the five episodes of this story. I won't spoil it too much but in this episode we do get that lovely infamous scene of Zoe draped across the TARDIS console...
This episode is pure 1960s' psychedelia. Peter Ling (the story's writer) pushes the boundaries of the show, and this story stands out from the rest of Troughton's other ones. Whereas most of his stories are famous for being monster mash-ups, we don't actually see the main baddie or alien in this story. We never learn who created the fictional world that the TARDIS crew find themselves in. And that makes it even more mysterious and eerie. (All the great science fiction and horror writers know that keeping your enemy hidden adds to the atmosphere of the story!)
This story leads directly into the next serial, The Invasion which is to be reviewed another time...