After losing a submarine and fifty crew in a battle with a German ship during WWII, a Royal Navy officer gets a second chance in a daring raid with midget subs.

Charles Nordeck is a successful marriage counselor whose own marriage is on the rocks. When his wife Anne seeks a divorce, Charles refuses to sign the papers fearing the bad publicity could ruin his career. The adulterous Anne then convinces her lover Peter to take care of the problem.

The time travellers arrive in Scotland just after the Battle of Culloden. The Second Doctor gains the trust of a small band of fleeing Jacobites by offering to tend to their wounded Laird, Colin McLaren. While Polly and the Laird's daughter, Kirsty, are away fetching water, he and the others are all captured by Redcoat troops commanded by Lieutenant Algernon Ffinch.