An alien serial killer is sent to Earth to live among humans as a punishment for his crimes, and his body is genetically transformed to look like a human. Nevertheless, the transformation is incomplete and every few hours the alien's body begins to revert to its original form, causing his head to explodes. The situation prompts the alien to "borrow" heads from anyone who happens to be nearby. He gets it by squeezing the head off with a crab-like claw and skewering it onto his own neck. At the same time, Detectives Pierce (Chong) and Krieger (Gordon) try to figure out who is causing the killing spree, with only one clue: all the heads of the victims have been removed and are lost. The team slowly comes to the conclusion that they are facing a rather unearthly killer.