On a United Aerospace Corporation (UAC) base on Phobos, Dr. Betruger prepares to teleport a volunteer from Phobos to a UAC lab in Nevada by using ancient teleporters known as “Gates.” The experiment proves successful, however, the subject emerges partially deformed. On a UAC transport vessel, a group of Marines awaken from cryosleep. They are on a mission to guard the Phobos base. Amongst them is Joan Dark, a disgraced lieutenant they are reluctant to work with. Joining them is Bennett Stone, a scientist and ex-boyfriend of Joan. Against Dr. Kahn’s wishes, Betruger prepares to teleport himself to the Nevada base. After preparations by Veronica, Betruger passes through the Gate. However, the Phobos base suddenly goes offline as monsters emerge from the Gate.