Ian Saynor

Looking for the final segment of the Key to Time, the Doctor and Romana arrive on the planet Atrios which is in a major nuclear war with the neighbouring world of Zeos.

Journeying to Zeos by transmat, the Doctor finds that it is an empty world. As the Marshal prepares to launch his final attack, the Doctor meets the commander of Zeos's forces.

The tragic truth of the sixth segment of the Key to Time is revealed and if the Black Guardian can control the Key, the whole of time and space will be plunged into eternal chaos.