Madame et le Mort plot
Armand Le Noir, famous author of police novels, is invited to give a lecture somewhere on the Côte d'Azur. At the last moment he learns that his arrival has been canceled by a telegram signed by him: but he himself knows nothing about it. Someone else has taken his place: Léopold Marion, flanked by two henchmen, Nazarian and the one-armed Avril. The real and the fake Le Noir take the same train to Paris. The second is killed and his corpse is thrown from the train. When the real Le Noir arrives in the capital, he learns through the press that he was murdered.