Aliens blow up Earth spacecraft in order to prevent the "contamination" of Earth's inhabitants from expanding.
Competent little Corman quickie made to cash in on the launch of Sputnik is nothing stupendous, but given it was in theaters a mere eight weeks after work started on the script, it's pretty darn good. Plus any movie that gives star billing to Dick Miller deserves some kudos. Devon gets acting honors, though, while Cabot's character is dim even by 1950s standards for female sci-fi characters.
Best line: "It can't be Sputnik; it's not listed in TV Guide." :P