When a scientific expedition is launched to study a mysterious alien race, the only ship available is the Nightflyer, a fully autonomous vessel manned by a single human. But Captain Royd Eris remains locked away, interacting with his passengers only as a disembodied voice--or a projected hologram no more substantial than a ghost. Yet that's not the only reason the ship seems haunted. The team's telepath, Thale Lasamer, senses another presence aboard the Nightflyer--something dangerous, volatile, and alien. Captain Eris claims to know nothing about the elusive intruder, and when someone, or something, begins killing off the expedition's members, he's unable--or unwilling--to stem the bloody tide. Only Melantha Jhirl, a genetically enhanced outcast with greater strength, stamina, and intelligence than other humans, has a chance of solving the mystery--and stopping the malevolent being that's wiping out her shipmates. But first she has to keep herself alive.