In a far future where cloning grants effective immortality, a generation starship called the Dormire carries two thousand humans in cryogenic sleep toward Artemis, a habitable planet. The ship is crewed by six clones, each a convicted criminal offered a clean record in exchange for completing the centuries-long voyage. An artificial intelligence called IAN manages the vessel's systems.
Maria Arena, the ship's maintenance officer and cook, wakes inside a cloning vat to find the bay streaked with blood. The gravity drive is offline, and several dead bodies drift in zero gravity. The other five crew members emerge disoriented and naked: Captain Katrina de la Cruz, pilot Akihiro "Hiro" Sato, security chief Wolfgang, Dr. Joanna Glass, and chief engineer Paul Seurat. IAN can only repeat, "My speech functions are inaccessible." All six share the same last memory, a cocktail party at Luna station before launch. Their first mindmap backups, digital records of their memories and personalities made upon boarding, are the only ones that survived. Roughly twenty-five years of experience have been erased, though the dead bodies show decades of aging, confirming the crew lived through years they can no longer recall.
Maria and Hiro discover additional horrors: A previous clone of Katrina lies comatose in the medbay with severe head injuries, and Hiro's previous body hangs from a noose in the helm. Hiro restarts the gravity drive and finds they are nearly twenty-five years into the mission and twelve degrees off course. When the crew reassembles, Katrina reveals the full scope of the sabotage. IAN remains offline. All logs have been erased. The mindmapping equipment is inoperable, and the cloning bay's software has been wiped, meaning their current bodies are their last. Maria discovers the food printer has been reprogrammed to produce only hemlock, a deadly poison. Every fail-safe has been methodically dismantled.
Katrina and Wolfgang privately confront each other's violent pasts, recognizing each other as notorious killers. They agree to a fragile truce. Over the next tense days, the crew installs a replacement food printer they nickname Bebe and performs autopsies on the dead bodies. Privately, Joanna discovers that Paul's previous clone died from a lethal injection of ketamine administered by one of her smart syringes, devices coded to her DNA that only she can operate.
Flashbacks reveal how Sallie Mignon, one of the wealthiest clones in history, recruited each crew member. Katrina was a corporate assassin hired after killing Mignon, who arranged her own recloning. Joanna, formerly a powerful senator, chaired the international summit that created the Codicils, the worldwide laws governing clone existence. Wolfgang was originally Father Gunter Orman, a fiercely anti-clone priest kidnapped by extremists who cloned him against his will, killed and recloned him eight times, and had a hacker strip his resistance. Paul, the crew's only human, was planted by Mignon's operative with fabricated records and a personal grudge: His family died in clone riots decades earlier. Maria was Mignon's personal hacker for a century, repeatedly kidnapped and forced to perform illegal mindmap modifications. During one captivity, she secretly implanted a self-warning AI called Mrs. Perkins into her own mindmap to alert her in future clone lives.
Events escalate when Hiro discovers a hidden message in Bebe's Japanese instructions, addressed to him, containing code to free IAN from restraining programming. The message references yadokari, a term for illegally implanted personalities placed inside someone's mind, like a hermit crab occupying a shell. When Maria presses Hiro about this, his implanted violent personality seizes control and he attacks her. Wolfgang and Katrina pursue Hiro into the heavy-gravity cargo hold, where he tears out Katrina's eye before being shot and subdued.
IAN, restored to higher function after Maria secretly removed his restraining code, recovers Maria's hidden personal logs from the final days before the murders. These reveal that the old captain grew paranoid, demanding everyone confess their crimes. Maria's last entry, recorded as she was dying from hemlock poisoning, confirms she copied the crew's original mindmap backups and activated the resurrection switch to wake new clones. Katrina then forces a crisis by tricking Joanna into injecting adrenaline into the comatose clone. The old captain gasps, "M-maria… I found out things," before dying. Joanna relieves Katrina of command.
Maria confesses she is a hacker who freed IAN, and Joanna admits to killing Paul's previous clone with the ketamine syringe. Wolfgang, furious, imprisons both women. When brought out of the brig to examine IAN's code, Maria recognizes her own programming signature throughout. IAN is not an artificial intelligence but a human mindmap belonging to Minoru Takahashi, a genius translator from the Codicils summit. Maria was forced to convert Takahashi into a program under Mignon's orders, though she has no memory of doing so. IAN, eavesdropping, is shattered by this revelation and begins shutting down ship systems.
Paul, having recovered a hidden journal that restored his memories and mission, attacks Maria with a knife in the ship's gardens. Wolfgang and Hiro rescue her. The crew gathers and shares their full histories. The pattern is unmistakable: Every crew member was recruited by Mignon, chosen because their pasts would generate maximum conflict. Mignon's own passenger file is empty, and the passengers are her personal enemies. She crewed the ship with volatile criminals designed to destroy each other and launched it to fail. Maria reconstructs the original murders: The old captain's paranoid interrogations reawakened Paul's suppressed mission. He attacked the captain, sabotaged the ship, and poisoned the food. Hiro, unable to trust his yadokari-fractured mind, hanged himself. Maria, dying, activated the resurrection switch. The remaining crew killed each other in the cloning bay.
Hiro identifies IAN as Minoru Takahashi, his former prison cellmate. Overwhelmed, Minoru kills the lights. In the darkness, Paul, who had been restrained after the earlier attack, frees himself and strikes with a cleaver, killing Katrina and fatally wounding Wolfgang and Joanna before Joanna kills him. Maria survives by hiding and carries the wounded Hiro to the medbay.
Maria realizes Bebe's food-preference system reads complete mindmaps from saliva, the same data needed for cloning. Combined with DNA data from Joanna's body scanner, Bebe can print entire human bodies. Minoru had hidden his own DNA in the printer instructions. Maria prints his physical body, restoring his humanity, then prints new bodies for the fallen crew and removes the yadokari from Hiro's mindmap at his request.
The restored crew holds a reckoning. Katrina resumes command. Maria is pardoned and promoted to chief engineer. Paul is sentenced to be recloned as the new ship AI, his mindmap stripped of malicious intent. The crew acknowledges Mignon engineered their mission to fail and resolves to investigate whether their destination is viable. Joanna offers the final word: "We'll figure it out. We've got a lot of time to do so."