Retired police lieutenant Al Giardello is running for mayor when he is suddenly shot at a press conference. All of the detectives, past and present, clamor for an opportunity to help find the shooter.

Having just returned from a mission to Mars, Commander Ross isn't exactly himself. He's slowly becoming a terrifying alien entity with one goal -- to procreate with human women! When countless women suffer gruesome deaths after bearing half-alien offspring, scientist Laura Baker and hired assassin Press Lennox use Eve, a more tempered alien clone, to find Ross and his brood. Before long Eve escapes to mate with Ross.