Carnivorous aliens arrive unannounced at a Kansas family farm; two intergalactic bounty hunters soon follow, determined to blow them off the planet.

A space commander sends a female android to Earth to destroy an escaped convict.

Two aliens arrive on Earth trying to kill each other. This is not easy, since they seem to be able to regenerate lost body parts and survive bullet wounds. Both of them happen to meet a young pathologist Dori Caisson, and each alien tells her that he is a peacemaker (an intergalactic cop) and that the other one is a bad guy. Whom can she trust?