Julian DeRose was born into a bloodline that measures worth in strength, obedience, and usefulness—and by those standards, he is a defect. After a mission at Fort Giden leaves him on the edge of death, Julian survives by forging a forbidden pact with Zerodawn, a monstrous lunar entity with crimson eyes, a predatory smile, and plans of her own.

What begins as a desperate contract soon drags him into a world of broken orders, sick cities, ancient gates, and the people society discarded as disposable pieces. As enemies gather and the bond between boy and monster grows darker, stranger, and far more intimate, Julian must decide what he is willing to become: heir, weapon, executioner—or something the world was never meant to survive.