Ryland Grace is the sole survivor on a desperate, last-chance mission—and if he fails, humanity and the earth itself will perish. Except that right now, he doesn’t know that. He can’t even remember his own name, let alone the nature of his assignment or how to complete it. All he knows is that he’s been asleep for a very, very long time. And he’s just been awakened to find himself millions of miles from home, with nothing but two corpses for company. His crewmates dead, his memories fuzzily returning, Ryland realizes that an impossible task now confronts him. Hurtling through space on this tiny ship, it’s up to him to puzzle out an impossible scientific mystery—and conquer an extinction-level threat to our species. And with the clock ticking down and the nearest human being light-years away, he’s got to do it all alone. Or does he?

In a corporate-dominated spacefaring future, planetary missions must be approved and supplied by the Company. Exploratory teams are accompanied by Company-supplied security androids, for their own safety. But in a society where contracts are awarded to the lowest bidder, safety isn’t a primary concern. On a distant planet, a team of scientists are conducting surface tests, shadowed by their Company-supplied ‘droid — a self-aware SecUnit that has hacked its own governor module, and refers to itself (though never out loud) as “Murderbot.” Scornful of humans, all it really wants is to be left alone long enough to figure out who it is. But when a neighboring mission goes dark, it's up to the scientists and their Murderbot to get to the truth.

Each of the Empire's houses keeps secrets, even from themselves. For the bookish academics of the Sixth, every secret is a mystery, and every mystery is a puzzle to be solved or a paper to be published. Deep in the bowels of their house, one such secret is about to reveal itself. The study of the famed academic Donald Sex, sealed since the moment of his death, is about to open, and archivists are ready to dissect what he left behind. They are not ready for the macabre surprise that awaits them. Enter Palamedes Sextus and Camilla Hect, age thirteen.

The Emperor needs necromancers. The Ninth Necromancer needs a swordswoman. Gideon has a sword, some dirty magazines, and no more time for undead bullshit. Brought up by unfriendly, ossifying nuns, ancient retainers, and countless skeletons, Gideon is ready to abandon a life of servitude and an afterlife as a reanimated corpse. She packs up her sword, her shoes, and her dirty magazines, and prepares to launch her daring escape. But her childhood nemesis won't set her free without a service. Harrowhark Nonagesimus, Reverend Daughter of the Ninth House and bone witch extraordinaire, has been summoned into action. The Emperor has invited the heirs to each of his loyal Houses to a deadly trial of wits and skill. If Harrowhark succeeds she will become an immortal, all-powerful servant of the Resurrection, but no necromancer can ascend without their cavalier. Without Gideon's sword, Harrow will fail, and the Ninth House will die. Of course, some things are better left dead.