Anthony Ainley

The Doctor returns to Gallifrey only to discover that a deadly game banned and derelict for centuries, has been reactivated. Soon he finds his other selves have also been summoned to assist him in tracing the culprit and tracking down the secret Rassilon.

The Doctor has been taken from the Zero Cabinet by Castrovalvan warriors.

The Doctor seeks a solution to Castrovalva's temporal treadmill, which renders escape impossible.

While Nyssa and Tegan search for the zero cabinet on behalf of the Doctor, he studies the history of Castrovalva and discovers a trap.

Mel realises that the Valeyard has created a weapon within the Matrix that will destroy the Time Lords, and the Doctor is forced to rely on the Master for help.

The Valeyard's true identity is revealed and the trial aborted, but the Doctor and Mel must pursue a new enemy into the Matrix, where nothing is quite what it seems.