A military squad led by Capt. Tavernier and Lt. Rosen patrol a complex series of caves on an alien planet. They're there to protect a key mineral - now used on Earth to provide power - from invading bug-like creatures. The aliens aren't only dangerous they are deadly requiring the team to regularly inoculate themselves against infection. When they learn that Rosen has not been receiving her injections due to a malfunction, Tavernier makes it clear she'll be on her own at the first sign of infection. Their immediate concern is to take control of a processing plant that the bugs will shortly make operational. As her medication wears off, Rosen begins to see things in a different light.