Starship C57D travels to planet Altair 4 in search of the crew of spaceship "Bellerophon," a scientific expedition that has been missing for 20 years, only to find themselves unwelcome by the expedition's lone survivor and warned of destruction by an invisible force if they don't turn back immediately.

• Metro-Goldwyn-Mayer
• Walter Pidgeon
• Anne Francis
• Leslie Nielsen
• Warren Stevens
• Jack Kelly
• Earl Holliman
• Richard Anderson
• George D. Wallace