When the isolated U.S. military moonbase is bombarded by a rogue meteor storm, Colonel Gerard Brauchman (Christian Slater) and his small crew are cut off from Earth with their life support failing. Before long, the crew discovers the meteors harbor alien spores...and they're replicating. Now a vicious, shape-shifting predatory life form is loose inside the crippled facility, picking off victims one by one. Locked in a desperate fight for survival, Brauchman and the terrified remaining astronauts have one final mission... keep the creature from escaping the moon and finding a new food supply on Earth.