After receiving a series of messages from outer space all decoded to be "Mars Needs Women", the United States Decoding Center in Houston receives a visit from Dop, the leader of a group of five Martians on an experimental voyage to Earth. Because of a genetic problem, Martians are producing virtually only male offspring and thus need to import women for the survival of the species. The Martians' non-hostile mission is to bring back to Mars five fertile and single human women. Those at the Center see the mission as a hostile one and as such the Martians decide to carry out their mission as inconspicuously as possible without the cooperation of the authorities by posing as Earthlings. Of the potential women they spy which includes strippers, co-eds and flight attendants, the one they believe is the most conducive to success of the project is the beautiful Dr. Marjorie Bolen, an expert in space genetics. In pursuing her, Dop falls in love with Dr. Bolen. But the Martians have to complete the mission before the authorities, which includes Dr. Bolen, find their secret hiding location.