Having just returned from a trip to the Orient, French author Charles Regnier dines with his friend, Henry Borchard, at the Café du Bois in Paris. Though he has been hailed as a national hero following the publication of his latest book, Fraudulent Justice , Charles knows that the controversial book has made him an enemy of the government. During the meal, Charles begins to feel unwell, and leaves to take a walk through the city streets. Outside, Charles is startled and tormented by mysterious mental images of a cat and lightning strikes. That night, Devereaux, a librarian carrying documents incriminating Charles in a conspiracy against the government, is found clawed to death. Police begin an investigation and immediately suspect Charles, whose book concerned the famous trial of a "catman" murderer. Without Devereaux' documents, there is no evidence to link Charles to the murder, and the police decide to wait until they can prove conclusively that he is the killer before arresting him. Troubled by his frequent memory lapses, even Charles begins to wonder if he is the killer. Although he is engaged to Marguerite Duval, Charles enters into an affair with Marie Audet, the daughter of his publisher. Marguerite soon discovers the affair, and when she asks Henry to explain Charles' unusual behavior, Henry tells her that Charles must be suffering from a tropical fever. Late one night, Marguerite is approached by a man who screeches like a cat and kills her. The following day, while dining at a café with Marie, Charles is given a beating by a group of diners, who angrily accuse him of being the mysterious "catman" killer. Convinced that he is the killer, Charles prepares to turn himself in to the police and confess, but Marie, who believes that he is innocent, persuades him to remain silent. Henry, Charles and Marie then flee Paris by carriage and take refuge in a chateau, where Henry tells Marie that irrefutable evidence has been found linking Charles to both murders. Henry warns Marie that she is in danger of being the catman's next victim, and gives her his gun to protect herself. Late that night, Marie sees a man who resembles a cat at her window, and just as he is about to attack her, the police arrive and shoot him. Upon close inspection of the catman, the police discover that he is Henry. With his dying breath, Henry confesses to the murders and tells the police that his death will mark the end of his ninth and final incarnation on earth as the catman.