A guard discovers an unusual lifeform on her remote moon outpost. She disregards protocol to investigate it, with catastrophic consequences. The parasitic alien wears its victims' skins and adopts their personalities. It's a perfect disguise, and allows the creature to spread without being detected. By the time humanity realises it's facing extinction, a third of its six hundred space stations have already gone dark. As the alien's ruthless progress collapses communication networks, wipes out defences, and leaves hundreds of stations to fend for themselves, a handful of remarkable individuals must find a way to battle the greatest threat the universe has ever encountered.