The TARDIS brings the Doctor, Susan, Barbara, and Ian to the planet Skaro where they meet two indigenous races — the Daleks, malicious mutant creatures encased in armoured travel machines, and the Thals, beautiful humanoids with pacifist principles. They convince the Thals of the need to fight for their own survival.
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.
When the Doctor, Sarah Jane and Harry arrive in Scotland, having received an urgent request for assistance from the Brigadier, they discover that the mysterious force which has destroyed three oil rigs has left giant teeth marks on the wreckage. The mystery deepens, leading them to the shores of Loch Ness where they find that the legendary monster really does exist – and is the murderous tool of the Zygons, aliens intent on overpowering the planet. The Doctor, his companions and UNIT must find a way to defeat the deadly Loch Ness Monster and its controllers, but the Zygons have the terrifying power to change shape. The Doctor's life has never been in more danger, as the line between allies and enemies is tested to the very limit...
When the TARDIS malfunctions, it and its travellers land on Earth at the size of insects. They uncover a murderous plot involving a new insecticide, but how can they stop the crime in their miniaturised condition?
The TARDIS arrives in a desolate future London, where the Doctor discovers his old enemies the Daleks have taken control of Earth.
Commander Logar fools Arif and sends him 1.000.000 years back in the time. He must civilize people from past to reach today.
In ancient Rome, bathhouse architect Lucius (Hiroshi Abe) becomes famous with designing the original "thermae" (bathhouse). He receives an order to build a thermae in the colosseum to help gladiators recover from their wounds, but faces difficulties. Thus, Lucius travels again to modern day Japan through the time slip. He meets Manami (Aya Ueto) again, who is now a reporter for a magazine which covers bathroom. With the help of the flat face Japanese tribe, Lucius again designs a new thermae. Meanwhile, Emperor Hadrian (Masachika Ichimura) wants to keep the peace with the thermae, but the Senate wants to extend the land by using force. Emperor Hadrian and the Senate now have a confrontation and Rome becomes divided.
Writer H. G. Wells pursues Jack the Ripper to modern day San Francisco after the infamous serial killer steals his time machine to escape the 19th century.
The members of a sci-fi club accidentally spill Coke on the remote controller of an air-conditioner during summer and suddenly a time machine appears in their sweating bath-like clubroom.