From the New York Times bestselling author of Sorcery of Thorns and An Enchantment of Ravens comes a thrilling, "dark coming-of-age adventure" (Culturess) about a teen girl with mythic abilities who must defend her world against restless spirits of the dead.

The spirits of the dead 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 ravenous, hungry spirits. She would rather deal with the dead than the living, who whisper about her scarred hands and troubled past.

When her convent is attacked by possessed soldiers, Artemisia defends it by awakening an ancient spirit bound to a saint's relic. It is a revenant, a malevolent being whose extraordinary power almost consumes her--but death has come, and only a vespertine, a priestess trained to wield a high relic, has any chance of stopping it. With all knowledge of vespertines lost to time, Artemisia turns to the last remaining expert for help: the revenant itself.

As she unravels a sinister mystery of saints, secrets, and dark magic, Artemisia discovers that facing this hidden evil might require her to betray everything she believes--if the revenant doesn't betray her first.