Vespertine

Artemisia has spent her life training to become a Gray Sister, tending the bodies of the dead in the kingdom of Loraille so their souls can pass on instead of returning as vengeful spirits.

When soldiers possessed by something monstrous attack her convent, she has no choice but to unseal an ancient and extraordinarily dangerous spirit, a revenant named Rathanael, and bind it to herself. Rathanael's power can save her life, or consume her soul entirely.

As Artemisia learns to control the bond and uncovers a conspiracy involving corrupted holy relics, she realizes a far greater evil is stirring, one that only she and the revenant she fears might be able to stop.