Claude Isner's historical detectives march triumphantly across Europe and conquer the world. In the novel “Fatal Crossroads,” another complicated crime awaits its solution. The corpse of a young woman in a red dress with her face disfigured by acid was found in Montmartre. On the same day, Victor Legree is brought a red woman's shoe, to which is stuck a piece of paper with the name of his bookstore. Who was the murdered woman, and what does she have to do with Victor?..