Aboard the AKI—a spacecraft dedicated to biological research—Laura Lewis is pulled out of cryogenic sleep by the vessel's emergency systems. A detonation has torn through her deck. Something on the other side of a door marked E0 is breaking loose, and when the door finally gives, the hallway floods with light and a sound like nothing Laura has heard before. She reaches her crewmate Parker through the video phone above her sleep chamber in time to watch him reach for his weapon—and then watch him die, killed by something she cannot see. Armed and out of her quarters, Laura navigates a ship now overrun with invisible creatures, guided only by the aural warnings of her earring-shaped guidance system. Other crew members may still be alive. Getting to any exit means moving through whatever hunts the corridors of the AKI.