Major Dan Keller works for NORAD, at the computer control section. There he programs complex machinery that watches the skies, constantly. The aliens need a window to bring in a great many saucers, so that they may establish a base on a remote island. To do that, they place one of their own as Dan Keller's new wife Laurie. She is equipped to hypnotize Dan into replacing a crucial programming tape with one the aliens have forged - one that will instruct the systems to ignore certain things they see.