Roger Cunningham and his wife Valerie go on a camping trip with another couple and find themselves stranded. Arguments arise, and secrets begin coming out: accusations of affairs, marriages of convenience, and homosexuality
The Doctor and Romana follow a distress signal which leads to the jungle planet Chloris, whose ruthless ruler Lady Adrasta harbors a deadly creature in a pit.
When two belligerent Dominators and their robotic servant Quarks land on the peaceful planet Dulkis planning to drop a radioactive seed into the planet's core to refuel their spaceship, the Second Doctor, Jamie and Zoe must attempt to inspire the pacifist Dulcians to resist.
Aided by his two assistants Jamie and Victoria, the Doctor lands the TARDIS on Telos, last resting place of the infamous Cybermen. There he discovers a band of archaelogists on a secret expedition to unearth the reason for his old enemies' extinction. In the underground shadowy depths, they find the icy tomb. A whole army in hibernation. A threat to no one, if the temperature remains low. But if the traitor in their midst gets his way, things could really heat up.
The TARDIS arrives in 2070 on the Moon, where a weather control station under the command of a man named Hobson is in the grip of a plague epidemic — in reality the result of an alien poison planted by the Cybermen. Jamie is knocked unconscious and lapses into a delirium, leaving the Second Doctor, Ben, and Polly to fight off a massive Cyberman attack.
