From the New York Times bestselling author of Sorcery of Thorns and An Enchantment of Ravens comes a thrilling new YA fantasy about a teen girl with mythic abilities who must defend her world against restless spirits of the dead.The dead of Loraille do not rest. Artemisia is training to be a Gray Sister, a nun who cleanses the bodies of the deceased so that their souls can pass on; otherwise, they will rise as twisted spirits with a ravenous hunger for the living. She'd rather deal with the dead than the living, who point and whisper about the odd girl who was once possessed by a violent spirit. When her convent is attacked by possessed soldiers, Artemisia fights back by awakening an ancient spirit bound to a high saint's relic. It is a revenant, a malevolent being now whispering in her head. Wielding its extraordinary power almost consumes her in body and soul. But death has come to Loraille, and only a vespertine, a priestess trained to wield a high relic, has a chance of stopping it. Yet the age of vespertines has passed, their knowledge and training lost with time. As Artemisia investigates a mystery of saints, secrets, and dark magic, an ancient evil is stirring. Can an untrained girl, tormented by the burden of containing the revenant's devouring power, have any hope of defeating it?