The Doctor and Clara are on the most beautiful train in history but a deadly creature is stalking the passengers. The Doctor must race against the clock to defeat the terrifying Mummy.

Separated from the Doctor, Clara discovers a new menace from another dimension. But how do you hide when even the walls are no protection? With people to save and the Doctor trapped, Clara comes up against an enemy that exists beyond human perception.

One morning in every city and town in the world, the human race wakes up to face the most surprising invasion yet. Everywhere, in every land, a forest has grown overnight and taken back the Earth.

The Doctor takes Adric and a young air hostess named Tegan Jovanka, who has come aboard the TARDIS by accident, to the planet Logopolis, home of a race of mathematicians whose help he hopes to enlist in reconfiguring the outer shell of the TARDIS. The mysterious, wraith-like Watcher brings Nyssa from Traken to join them and warns of impending danger - something that is borne out as the Master arrives and kills a number of the Logopolitans.

The Doctor and Romana visit the Leisure Hive on the planet Argolis, the surface of which is uninhabitable following a twenty minute nuclear war between the Argolins and their enemies the Foamasi. The Argolins themselves are now sterile. Pangol, the youngest, was created by the Tachyon Recreation Generator, a machine that runs games in the Hive.

The Doctor begins a perilous mission to save all humankind from destruction.

The Doctor begins a perilous mission to save all humankind from destruction.