In 2284, two years after the Mars Base disaster, the United Terran Forces were preparing to invade the breakaway colony of Mendel, using the uncolonized world Epsilon Eridani F as a staging ground. The supercarrier Atlas was dispatched to construct the necessary facilities — but something deadly seized the ship. With the infection spreading, the last dropship has been sent in, carrying five seasoned space marines as humanity's final attempt to reclaim the vessel.