When lonesome astronomer Dr. Steve Mills (Dan Aykroyd) sees the extraordinarily beautiful but incredibly awkward Celeste (Kim Basinger) at a party, the last thing he would believe is that she is a space alien on a mission to do whatever it takes to save her planet, but he learns the truth when, despite her dubious intentions, he and Celeste decide to marry. Things get dangerous when Celeste's superior, whom she keeps in her magic handbag, decides to take care of matters himself.