A joint Anglo-American mission headed by Commander Tom Carlsen (Steve Railsback) explores an alien spacehip discovered inside Haley's Comet and finds a trio of naked slumbering humanoid aliens. When they wake up, the aliens make quick work of Carlsen's team, sucking the lifeforce from their unsuspecting bodies, and are soon charting the course back to Earth ready to take on the general population. Carlsen does his best to stop the invasion, but in no time at all London is placed at the wandering mercy of beautiful naked vampire space lady (Mathilda May) who has no moral compunction about either mass slaughter or her own state of constant undress.