On a survey of Pharos, the crew of XL5 disocver the planet is unstable and must be destroyed. After setting up bombs, someone traps Steve and the others in with it.
John Kelly
Director
Dennis Spooner
Writer
Gerry Anderson
Robert the Robot (voice) (uncredited)
David Graham
Lieutenant Ninety (voice)
Sylvia Anderson
Doctor Venus (voice)
Paul Maxwell
Colonel Steve Zodiac (voice)
John Bluthal
Commander Wilbur Zero (voice)