When a scientific expedition is launched to study an alien race, the only ship available is the Nightflyer - a mysterious ship whose equally mysterious captain remains locked away, refusing to interact with his new passengers in person. Worse, the mission's telepath, Melantha Jhirl, senses a presence aboard the ship: dangerous, volatile, and alien. And then, one by one, the passengers start dying. Only Melantha - genetically enhanced and able to think three steps ahead of most of humanity - has a chance of figuring out the mystery... if she can stay alive long enough.