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.
In response to political pressure from Senator Lillian DeHaven, the U.S. Navy begins a program that would allow for the eventual integration of women into its services. The program begins with a single trial candidate, Lieutenant Jordan O'Neil, who is chosen specifically for her femininity. O'Neil enters the grueling training program under the command of Master Chief John James Urgayle, who unfairly pushes O'Neil until her determination wins his respect.