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.
Tom Baker
as The Doctor
Mary Tamm
as Romana
John Leeson
as K-9 (voice)
Bruce Purchase
as The Pirate Captain
Andrew Robertson
as Mr. Fibuli
Rosalind Lloyd
as Nurse
David Warwick
as Kimus
David Sibley
as Pralix
Ralph Michael
as Balaton
Primi Townsend
as Mula
