A couple revisit a past love affair when they meet again ten years later.

Charles Dobbs is a British secret agent investigating the apparent suicide of Foreign Office official Samuel Fennan. Dobbs suspects that Fennan's wife, Elsa, a survivor of a Nazi Germany extermination camp, might have some clues, but other officials want Dobbs to drop the case. So Dobbs hires a retiring inspector, Mendel, to quietly make inquiries. Dobbs isn't at all sure as there are a number of anomalies that simply can't be explained away. Dobbs is also having trouble at home with his errant wife, whom he very much loves, having frequent affairs. He's also pleased to see an old friend, Dieter Frey, who he recruited after the war. With the assistance of a colleague and a retired policeman, Dobbs tries to piece together just who is the spy and who in fact assassinated Fennan.

The Doctor and Jo visit the Master in his high-security prison on an island off the south coast of England. The governor, Colonel Trenchard, says ships have been disappearing mysteriously at sea. The Doctor discovers that Trenchard and the Master are in league to contact the Sea Devils, a race of reptiles in hibernation in a base beneath the sea, who have been awoken by recent work on a nearby sea fort. The Master intends to use his new allies to help him conquer the world!

When the TARDIS lands in the sea off the eastern coast of England, the Second Doctor, Jamie, and Victoria investigate a nearby beach, which seems to have an improbably large amount of sea foam as well as a major gas pipe marked “Euro Sea Gas” What is really happening at "Euro Sea Gas." Can the Second Doctor, Jamie and Victoria survive "The Fury from the Deep"!

A young policeman becomes involved with a glamorous German woman in London, to his cost.

Solicitor Alan Phipps formulates a plan to blackmail his wealthy and unfaithful wife, Yvonne, and at the same time, get revenge against her boyfriend, John Brodie, by setting him up to appear that he is the blackmailer and for Yvonne to kill him.