When New Orleans detective Reuben Montoya is called to investigate the murder of a nun, he's shocked to recognize the victim. Sister Camille was his high school girlfriend. And she’s just been found on the altar of St. Marguerite's cathedral…viciously garroted.

Before devoting herself to god, Camille had a knack for making bad choices. She joined the convent after falling for her sister Valerie’s soon-to-be ex-husband. But as Val—a former Texas cop—digs into Camille's murder, she realizes how little she really knew about her sister and their shared past.

As more women of the church are found brutally slaughtered, no one is beyond suspicion—not even Friar Francis O’Toole. And no one is safe—least of all Valerie. Because this killer knows all, forgives nothing, and will not rest until Valerie becomes the next to pay for her sins.