«Great Day for the Deadly» by Jane Haddam

Her childhood friends wanted careers, but Brigit Ann Reilly spent her youth looking forward to her wedding-her wedding to God. When she finally gets to don the habit, her new order sends her to Maryville, where a former sister is poised to become Rome’s first Irish-American saint. Brigit has no time to worry about Vatican politics. She’s about to become a martyr herself. Brigit is found dead in the basement of her local library, her corpse swarming with ten poisonous water moccasins. When ex-FBI investigator Gregor Demarkian hears of her death, he is puzzled by two things: Water moccasins are not native to upstate New York, and Brigit died of hemlock poisoning, not the snakes’ venom. As Maryville whips itself into a pious frenzy in search of evidence for its hometown hero’s sainthood, Demarkian will attempt his own miracle by finding justice for the murdered young nun.