Elizabeth is kidnapped, one of dozens of scientists held prisoner on the island of Felicitos, controlled by special mineral springs that render their victims completely happy and compliant. Dr. Smith is using them to build a rocket to take her away from our troubled planet in search of some better world, and Mark must find a way to counter the brain-washing and free the captives.

Patrick Duffy
Mark Harris

Belinda Montgomery
Dr. Elizabeth Merrill

Kenneth Tigar
Dr. Miller Simon

Alan Fudge
C.W. Crawford

Darleen Carr
Dr. Mary Smith
Dennis Redfield
Dick Stoneman
Pamela Peters Solow
Jane

Fred Beir
Captain Bracy

Paul Mantee
FBI Agent Fuller
Michael J. London
Cetacean Crewman

Arthur Batanides
Police Detective

Rick Goldman
Security Guard at Dock

Bob Minor
Minion
Ric Drasin
Minion
Frank Martone
Minion