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.
- Genre: Science Fiction
- Studio: Metro-Goldwyn-Mayer
- Keyword: flying saucer, space, alien planet, rescue mission, robot, electronic music score, sabotage, shakespeare in modern dress, mysterious death, alien civilization, lone survivor, extinct race, invisible monster, ray weapons, mind enhancement, atomic power plant, romantic triangle, creation of matter, misanthropy
- Cast: Walter Pidgeon, Anne Francis, Leslie Nielsen, Warren Stevens, Jack Kelly, Marvin Miller