The novel takes place in Paris in 1750. The mutilated corpse of a secular beauty is discovered in the Innocents Cemetery. It soon becomes clear that the killer's traces lead to the fashionable Parisian salon of the Marquise de Grammont, but Abbot Joël de Saint-Severin, who guesses about this, is perplexed: there are too many people in the salon who simply cannot be suspected, while those who arouse suspicion with their obvious sinfulness are obviously innocent ... But the detective component is not at all the main thing in the novel. Abbé Joel sees the reasons for the blasphemous abominations being committed in the new distorted thinking of people, in the quirks of the “Voltairian” mind...