English explorer Travers is determined to track down the mythical Abominable Snowmen which are said to roam the Himalayas. When the Doctor and his companions visit the nearby Detsen monastery they discover that the Yeti are all-too prominent. In fact, they are out to kill anyone who comes near. With Travers' help the travellers discover that the monastery is in the grip of the evil Great Intelligence, a disembodied force which has taken control of the High Lama....

When the Doctor, Polly, and Ben visit a human colony that appears to be one big holiday camp they think they have come across a truly happy place. But a shadowy presence soon makes them realise that the surface contentment is carefully controlled. The colony's inhabitants have been brainwashed by giant crab-like creatures - the Macra. Insidious propaganda, broadcast by the Controller, forces the humans to mine a gas that is essential for the Macra to survive - but fatal to them. The colony must be saved - but how?

The TARDIS arrives on an extinct volcanic island, beneath which lies a fantastic subterranean world inhabited by the primitive Atlanteans. The Doctor and his companions move from the frying pan to fire when they are rescued, from death at the jaws of hungry sharks, by the mad Professor Zaroff, whose plans involve nothing less than the destruction of the whole world.

The travellers arrive in the dangerous domain of the Toymaker, where their failure to win at a series of games could result in them becoming his playthings for eternity. Apparently innocuous nursery characters reveal deadly intent, and for companions Steven and Dodo the stakes are raised with every game of blind man's buff and musical chairs. The Doctor, meanwhile, is rendered invisible and given the challenge of completing the fiendishly difficult Trilogic game.

Patrick Troughton witnesses 'the final end' of the Daleks in this exclusive recording of a classic 'lost' BBC television adventure, with linking narration by Frazer Hines.