Colonel Gerard Brauchman and his crew are working on a lunar mining base Ark when a meteor storm strikes. While investigating the damage, the crew discovers alien spores which can reproduce rapidly. Now a horrible, shape-shifting predatory life form is loosing within the base, attemping to poison and kill victims one by one. Brauchman and the horrified remaining astronauts now have one last chance to save their own lives and the entire human...stop the montrous creature before it leaves the moon and search for a new food supply on Earth.