A team of American astronauts leave their space station on the first mission to Mars, but the captain's religious beliefs may get in the way.

Walter Brooke
as Gen. Samuel T. Merritt

Eric Fleming
as Capt. Barney Merritt

Mickey Shaughnessy
as Sgt. Mahoney

Phil Foster
as Jackie Siegle

William Redfield
as Roy Cooper

William Hopper
as Dr. George Fenton

Benson Fong
as Imoto

Ross Martin
as Andre Fodor

Vito Scotti
as Sanella

John Dennis
as Donkersgoed