The HAUNTED MARTYR plunges the American novelist Denton into the world of turn-of-the-century spiritualism, most of which is sham but which includes some very real death. It is the winter of 1902-1903. Denton has brought his lover, Janet Striker, to Naples, Italy, to recover from a near-fatal attack of typhus. Denton is using the advance from a book to pay his expenses: the book centers on spiritualism and the supernatural in Naples. (Several seances are with Eusapia Paladino, a real historical figure and an object of study by England's Society for Psychical Research.) Denton intends to write a light travel book on spiritualists, ghosts, legends and horrors, and on Naples itself. But when he tries to rent a newly-renovated palazzo and is told by the agent that he can rent it for free if he dares first spend a night there, he knows the place must be haunted. He and Janet duly see an apparition of a tall, long-armed woman, an apparition which leads inevitably to the discovery of a real body, to the story of an eccentric English peer with a terrible secret and the involvement of the Comorro - the Neapolitan mafia.