The mission for Captain Taverner and his squad of North American Federation (NAF) soldiers is simple: search and destroy invading aliens on a distant planet to prevent them from stealing a mineral which is a vital source of energy for earth, and a vital source of profit for the NAF. To guard against infection from the hideous bug-aliens, the soldiers are forced to inject special genetic drugs; however, the mission becomes complicated when Lieutenant Rosen is wounded in a firefight with the aliens. Rosen begins to hallucinate, experiencing disturbing images of the aliens, and when she discovers that her druginjector has malfunctioned, she begins to suspect that the drugs do more than protect the soldiers from infection. Ultimately, Rosen must take command and risk the lives of her soldiers on the hunch that their mission may have more to do with human politics than alien enemies.