The Doctor and Romana learn the second segment of the Key to Time is on the planet Calufrax. Yet they arrive on a planet called Zanak, which has been hollowed out and fitted with hyperspace engines, allowing its insane, half-robot Captain to materialise it around smaller planets and plunder their resources.

Action, Adventure, Drama, Science Fiction, TV Movie

Tom Baker, Mary Tamm, John Leeson, Bruce Purchase, Andrew Robertson, Rosalind Lloyd