Vespertine

Artemisia is training to become a Gray Sister, one of the nuns who prepare the dead so their souls can move on. Neglect those rites and the departed return as starving, restless spirits. She would rather keep company with corpses than with the living, who whisper about her scarred hands and the troubled past behind them.

When possessed soldiers storm her convent, Artemisia drives them back by rousing an ancient spirit bound to a saint's relic. The creature is a revenant, and its strength nearly consumes her. With death now loose in the land, only a vespertine, a priestess trained to wield a high relic, has a real chance of stopping it. Knowledge of vespertines has been lost for ages, so Artemisia seeks out the only surviving authority on revenants.

Her search leads her into a tangled puzzle of saints, buried secrets, and forbidden magic. As the danger deepens, she begins to suspect that confronting it may force her to abandon the beliefs she has always held, and that the revenant she has called forth may turn on her before she can control it.