Nina Kane, sixteen, lives in New Temperance, where sins are viciously prosecuted by the Church. Their world is one of demons, soul-eaters, and if Nina and her sister, Mellie, are not careful, their souls will be gone, too. When Nina learns of Mellie's dangerous secret, the sisters band together, along with a hoodie-wearing exorcist who is not part of the Church, to save their souls from darkness.