When the ice hauler Canterbury was destroyed by a hidden stealth ship, XO Jim Holden and a handful of survivors ended up aboard the stolen Martian corvette Rocinante, while on Ceres detective Miller was assigned to find runaway heiress Julie Mao. The two threads converged on Eros, where Julie lay dead of an alien contagion and the corporation Protogen was secretly using the station's million and a half people as a live test of the 'Phoebe protomolecule'—an ancient alien weapon—hiding it behind a manufactured Earth-Mars-Belt war. Holden's crew and Miller allied with OPA leader Fred Johnson, stormed Protogen's Thoth Station, and captured its architect Dresden, whom Miller executed. When their attempt to ram Eros into the sun failed—the protomolecule seized control of the whole station and drove it toward Earth—Miller stayed behind, found Julie's mind alive and steering it, let the protomolecule take him so he wouldn't leave her, and convinced her to divert Eros to Venus instead, sacrificing them both. Eros came apart into a seed cloud across Venus, and Earth was saved.
Recently, weeks later, the surviving powers gather on neutral Ceres for a peace conference, with Fred Johnson holding the only protomolecule sample as leverage over an Earth and Mars pushed toward lasting war by Protogen's betrayal—while Venus stirs with unexplained two-kilometer crystal towers, proof the alien thing is far from finished. Holden, recovering from the punishing chase, presses Fred for amnesty, salvage rights to keep the Roci, and above all that Miller be honored by his true name, Josephus Aloisus Miller—a flawed, difficult, real man—rather than reduced to a faceless icon of Belter sacrifice. Fred, intent on using the symbol regardless, takes the podium and reframes humanity's choice: on one hand mutual annihilation, on the other the stars.