The Novelist Durtal is disgusted by the emptiness and vulgarity of the modern world. He seeks relief by turning to the study of the Middle Ages and begins to research the life of the notorious 15th-century child murderer, sadist, necrophile, and practitioner of all the black arts - Gilles de Rais. Through his contacts in Paris Durtal finds out that Satanism is not simply a thing of the past but alive in turn of the century France. He embarks on an investigation of the occult underworld with the help of his lover Madame Chantelouve. Durtal's preoccupation with Gilles de Rais's lascivious brutalities begets in him the urge to find out if similar satanic practices are still performed; so he persuades Madame Chantelouve to take him to the house of a notorious renegade priest named Canon Docre. Together they witness there the celebration of a Black Mass, and few finer descriptions of this obscene ritual have ever been written. French Victorian Gothic as its best.