Durtal is writing about Gilles de Rais, the child murderer believed to be the source of the legend of Bluebeard. He takes comfort in writing about the past, away from what he perceives as a immoral & decadent present (the novel was published in 1891). He finds himself embroiled in Satanism, witchcraft, & in a scandalous affair with the elusive madame Chantelouve. A strong story with philosophic elements, the novel still has a potent shock.