In eighteenth-century Honfleur, a child is born with a horrific destiny before him. His name is Latour, and his mother raises him with tender care, even when it becomes clear there's something deeply wrong with the boy - he is physiologically incapable of feeling pain. After serving an apprenticeship with a local taxidermist, Latour leaves home with Valerie, the town whore, to explore the lower depths of Paris. Obsessed by his abnormality and fascinated by the mysteries of pain, Latour loses himself in a dark spiral of death, murder and dissection in his attempts to fathom the secrets of the human body. Through Valerie, Latour eventually meets the infamous Marquis de Sade, whose faithful servant and accomplice he becomes.