For Flight Engineer Cynthia Han and her fellow astronauts aboard the International Space Station, Expedition 81 has proved as mundane as space travel ever gets. Yes, this would be Cynthia’s final NASA mission, for reasons she’s so far kept from the rest of the crew; and yes, the latest billionaire “space tourist” has managed to irritate everyone on board. Still, none of them could have asked for a smoother experience. Until the morning they wake up to silence. All communication with Earth, gone. From half a dozen different agencies with multiple installations and redundancies across the globe, there is simply... nothing. And through the viewports of the ISS, only the thick veil of churning, lightning-veined dust to suggest the Earth remains at all. Now, without ground control, without the proper telemetries or calculations or even reliable visuals, Cynthia and the rest of Expedition 81 must make their way home. For most, it will be the most fraught and the most frightening task of their lives. But it will be nothing compared to the world that now awaits them beyond the dust.

The world has ended. Along with other scattered survivors, astronaut Cynthia Han and the remainder of ISS Expedition 81 have finally learned what happened to the people they’d left behind, and it’s worse than any of them could have imagined. But even if life as Cynthia knew it is over, her struggles most certainly are not. Joshua Lamb, granted strange and inhuman abilities even as civilization died around him, directs his zealots to scoop up every pocket of survivors, to offer them the simplest Join or die. The nightmarish Crooked Men still hunt the darkened, hollowed cityscapes. And towering over it all, the mind-breaking obelisks with their unreadable alien message. At stake are not just the lives of Cynthia and her companions, but the last flickering embers of the human race. To succeed, not only must she learn the true purpose of the obelisks, she must come to understand that the worst of humanity’s instincts and sins were never limited to us alone.