The TARDIS arrives in a desolate future London, where the Doctor discovers his old enemies the Daleks have taken control of Earth.

On the planet Dido, the Doctor, Ian and Barbara meet two survivors from a crashed spaceship who are terrorised by the monster Koquillion.

The TARDIS crew take up residence near Rome in 64AD, where Ian and Barbara are kidnapped by slave traders, and the Doctor's imitation of Maximus Pettulian sees him taken to the court of Emperor Nero where he inadvertently plays a part in deciding the course of history...

On the planet Vortis, the Doctor and his companions aid the butterfly-like Menoptra in their battle against the parasitic Animus and its mind-controlled minions, the ant-like Zarbi.

In 12th century Palestine, the Doctor and his friends are drawn into the holy war between the forces of King Richard the Lionheart and the Saracen ruler Saladin.

On the planet Xeros, the TARDIS crew discover their own future selves frozen in time as exhibits in a galactic museum and must avert this potential future.

The Doctor and his companions are pursued through time and space by the Daleks on the desert planet Aridius and beyond.

In England, 1066, the Doctor confronts a mysterious Monk who is attempting to change history.

Ronnie's party is going well, but his mother Alice is waiting for her husband Tom to return from the office to help supervise. The doorbell rings, but instead of Tom it's Simon Potter, a strange little boy who Ronnie dislikes, and who knows some unusual and horrifying variations of children's party games.

The TARDIS has arrived on a far-distant and seemingly idyllic world. Yet the Doctor, Steven and Dodo learn it hides a terrible secret: the apparently civilised Elders maintain their advanced society by draining and transferring to themselves the life-force of the defenceless Savages.