In the desolate aftermath of the Quiet Rapture—where stars and worlds have vanished without a trace—the last fragile remnants of humanity cling to existence amid crumbling stations in the void. A lone convict, sealed inside a rusting, windowless submarine known as the Iron Lung, is plunged into the crimson depths of an alien moon’s endless ocean of blood. Promised freedom for his impossible mission, he navigates crushing darkness and unknowable horrors, where every sonar ping and fleeting glimpse through a grainy camera reveals something ancient, impossible, and terribly awake.