A math wunderkind from a breeder- world slum will sacrifice anything to become a soldier-even her own identity. Born into a society sculpted by endless war, Gaby dreams of fighting on the front lines. But the Intelligence Division has other uses for her talents and sends her to witness a top-secret training exercise on an experimental starship. When a violent mutiny overtakes the ship, Gaby's left alone to protect the ship's secret weapon: Passenger, a symbiotic artificial intelligence that can join with a human to hack other AIs, turning the tide of any battle, perhaps even the war. But the only way to keep the AI out of the mutineers' hands is to keep it in her head, and Passenger wasn't meant to stay integrated with a human for long. With no rescue in sight, and the barrier between Gaby's mind and the machine's deteriorating, she must do more than evade capture: She'll need to fight back.