London, 1963, and the Doctor returns to Coal Hill School with his new companion Ace, where he has unfinished business. His oldest foes,the Daleks, are on the trail of Time Lord technology – an artefact the Doctor himself left behind on Earth.

Enlisting the assistance of the local military, the Doctor must protect the Gallifreyan secret of time travel as two opposing Dalek factions meet in an explosive confrontation, with the fate of the entire Universe at stake!