The Doctor and his companions Steven Taylor and Dodo Chaplet arrive some ten million years into the future, on board a generation starship which is carrying the last of humanity away from an Earth that is about to fall into the Sun. However, the cold that Dodo has could prove devastating to these future humans and their servants, the Monoids.

Charles Dennistoun, a 60-year-old contestant on 'You Bet a Million' - a quiz show for millionaires - wins the jackpot prize, a course in rejuvenation. But his friends and family have mixed feeling, and the repercussions have blackly comic effects on all concerned.

The future. The material needs of people are tended by the Machine, which makes their environment, in vast tunnels beneath the earth, comfortable and safe. But if the Machine stops, what then?

A stranger calls at the home of divorcée Anna Preston, asking to collect some of her ex-husband's belongings. Anna agrees, but is suspicious, and tries to contact her 'ex' at the space-research establishment where he worked. But none of his colleagues can tell her where he is and the authorities block all her efforts to find out. Anna grows more convinced that he is in danger, but the truth is more horrifying than even she can imagine.

The future. The TAU-mode shuttle carries passengers to Australia through the earth's crust. When a routine TAU-shuttle becomes entombed in solid rock miles under the earth, the only means of rescue is the experimental LAMBDA-mode shuttle; which its creator is unsure about.

Level 7 is the deepest and the safest level in a nuclear bunker. The nerve centre of the government is based here. But how safe is it?

Déja vu: as Guy Birkett goes through the day he has a nagging feeling that he's been here before, experienced this already; except the details are always different. Is it conceivable that he is merely a simulacrum, the ultimate in consumer market surveying?

College student Sarah Richards is alone in fearing and disliking the new teaching machines but even she does not foresee the terrifying situation that arises when her supervisor, Stephen Kershaw, re-arranges the machines to conform with revised fire regulations.

Julian Clay is accused of murdering Andrew Maddox - a charge he cannot deny because 'The Eye', a device which records the past, saw him do it. However, the law affords one loophole.

Amos Handworthy's grandfather was quick on the draw: as a U.S marshal, it was a job requirement if you wanted to stay alive. But now Amos has built a gun-slinging robot, programmed to be a split second slower than him in a gunfight, so that he can perpetuate the myth and glory of his grandfather's frontier past. But will Amos bet his life on a duel with real bullets?