Falder and Lendi are apprentice God Keepers, engineer priests who command the ancient nanotechnology powering their civilization. While rebellious Lendi dreams of fleeing for a life of adventure, devout Falder is desperate to keep his best friend from abandoning their order—and him. But, when an ancient machine god crashes to the planet in a ball of fire and gray death, it severs all Keepers from nanotech, plunging the world into chaos.

Meanwhile, Sedna and Renfrik have little patience for Keeper rules or mysticism—the heir apparent to her warrior clan and her soft-hearted (but lethally skilled) brother are too busy protecting their remote, mountainous home from raiding bandits. But, when a flood of malfunctioning nanites in the god’s wake consumes their town, they’re left with nothing to protect but each other.

Falder and Lendi seek the god to restore the Keepers’ power, but Sedna and Renfrik just want revenge. As the foursome bands together on their hunt, they uncover vast archives of ancient knowledge and encounter a supposed servant of the gods. Cities burn, and new epicenters of nanite death cascade around them, changing everything to gray dust. To stop the god, the four must set aside their suspicion of each other, their pride, and even faith. Failure means dooming the world to divine wrath, but reestablishing the Keepers’ power—and learning the dark truth behind it—will force them to choose between saving each other and mending a shattered world.