In Avermouth, a sunken naval fleet sealed into a pressurized undersea city, air functions as currency and every resident wears a weekly breath mark counting down their supply. Tela Iguri, a twenty-three-year-old junior quartermaster of Hull Six, discovers that her superior has been secretly selling next month's air to Hull Three, where Tela's younger brother sleeps between shifts. Exposing the crime would spare Hull Six a devastating audit purge, but stopping the trade means opening a valve that would flood the deck above the stolen reserves. With only six days left on her own breath mark and no witness willing to risk suffocation, Tela must decide who deserves to keep breathing, who gets reduced to a number, and whether becoming an honest quartermaster means inheriting the very crime she condemned.
