The Doctor arrives on Gallifrey, where he is accused of the assassination of the Time Lord President. Investigating with the aid of Co-ordinator Engin and Castellan Spandrell, he discovers that this is part of a plot hatched by his old adversary the Master.

Barbara is captured by antlike Zarbi, under attack by the Menoptera, who hope to regain their planet. With William Hartnell.

Antlike Zarbi capture Barbara.

A mysterious woman who can't even remember her own name, falls from the sky.

The Doctor initially believes the TARDIS has landed aboard a clipper ship.

Set in Amsterdam in the early 1980s. Tegan's cousin is caught up in strange forces while on a backpacking holiday. The Time Lords are worried about the possible return of an old enemy and the only way to stop him is to execute the Doctor.

On the planet Manussa, in an unknown time. It is unknown how or why Tegan has steered the TARDIS here unconsciously. The planet is about to celebrate the 500th anniversary of the expulsion of devious Mara.

The Doctor discovers a starship trapped in a time warp over the planet. Meanwhile, public schoolboy and secret alien Turlough crashes his math teacher's vintage car. The Black Guardian makes him an offer.