Arthur Burdon, a renowned English surgeon, is visiting Paris to see his fiancée, Margaret Dauncey. On his first evening in Paris, Burdon meets Oliver Haddo, who claims to be a magician and has a fight with him. In revenge, Haddo uses both his personality and his magic to seduce Margaret, despite her initial revulsion towards him. They get married and run away from Paris and Arthur promptly returns to England to immerse himself in his work. In London, Arthur meets Margaret alone and she suggests that her life is threatened by her new husband. She implies that Haddo is only waiting for the right time to perform a magical ritual, which will involve the sacrifice of her life. Arthur seeks advice from his mentor and Haddo's acquaintance, the retired doctor and occult scholar Dr. Porhoët, but they must act fast as it might be too late for Margaret.