In the science-fiction thriller Species (1995), Natasha Hentsridge appeared as the beautiful but deadly Sil, a human-alien DNA combo. In this sequel, Hentsridge portrays Eve, a government experiment concocted to gain an understanding of how to combat future aliens, while Michael Madsen and Marg Helgenberger repeat their roles from the earlier film. When astronaut Patrick Ross (Justin Lazard) returns from the first manned Mars expedition, he's infected with the same DNA that spawned Sil and Eve. Hailed as a hero, Ross is pressed into politics by his father (James Cromwell), a senator. Any woman who beds the sexually active Ross is immediately impregnated, with embryos quickly developing and killing the mother. Ross hides the offspring on a family estate, as LA cops begin to detect a pattern in the female deaths. At the lab where scientists are monitoring Eve, Dr. Laura Baker (Helgenberger) realizes that Eve has a telepathic link with Ross, and that these two hybrids hope to couple. Press Lennox (Madsen) and Colonel Burgess (George Dzundza) figure Eve can be used to lead them to Ross. Cleared as a murder suspect, Mars mission astronaut Dennis Gamble (Mykelti Williamson), joins Lennox and Baker and gets in on the action as everyone involved closes in on Ross. Richard Belzer does a cameo as the President of the U.S., while Peter Boyle makes an uncredited appearance as a scientist.