Doc McCoy is put in prison because his partners chickened out and flew off without him after exchanging a prisoner with a lot of money. Doc knows Jack Benyon, a rich "business"-man, is up to something big, so he tells his wife (Carol McCoy) to tell him that he's for sale if Benyon can get him out of prison. Benyon pulls some strings and Doc McCoy is released again. Unfortunately he has to cooperate with the same person that got him to prison.

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. Government agent Xavier Fitch assembles a team of scientists and mercenaries to locate and destroy Sil before she manages to find a mate and breed.