The inhabitants of Ganymede need to find mates from another world or they will become extinct. They soon discover a suitable breeding stock amongst the females of planet Earth.
John Saxon
as Dr. Jack Costain
Patricia Haines
as Ann Barlow
Alfred Burke
as Detective Supt. Hartley
Maurice Denham
as Dr. Morley
John Carson
as The Major
Ballard Berkeley
as Cmdr. Savage
Stanley Meadows
as Det. Tom Grant
Barbara French
as Joyce Malone
Robert Crewdson
as Medra
Aubrey Morris
as Thorburn
Jack Watson
as The Sergeant
Tony Wager
as Pvt. Higgins
