In 1993, the Search for Extra Terrestrial Intelligence Project receives a transmission detailing an alien DNA structure, along with instructions on how to splice it with human DNA. The result is Sil, a sensual but deadly creature who can change from a beautiful woman to an armour-plated killing machine in the blink of an eye.

After she delivers her child in an ambulance, alien Eve is killed by a half-breed. Fortunately, Dr. Abbot scoops up the baby alien and escapes. In time, the baby grows into a gorgeous blonde named Sara and begins her quest to find a worthy mate. But Sara is also savage and leaves a trail of deaths in her wake. This carnage makes chemistry student Dean question whether to help her race or not.

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.

A scientist, Dr Holander, takes his niece Miranda to Mexico in an attempt to reverse the effects of the alien DNA he used to create her. However the treatment goes horribly wrong, and sets Miranda on a killing spree as she sets out to find a mate.