Beadle's Dime Library No. 561

Catalog Note This issue of *The Falcon Detective's Invisible Foe*, serialized by Jackson Knox (author of *The Circus Detective* and *The Sphinx Detective*), opens with a mystery in the Paris Police Rogues' Gallery. Joseph Isaacstein, a Dutch diamond merchant, becomes transfixed by photograph #2197—George Brookton, a serial murderer known as "the Thug King" or *le Monarque des Étrangleurs*, who kills by strangulation. Isaacstein senses premonition connected to the criminal's face. The merchant later has his ward, a young girl named Leah, forcibly abducted from a crowd near Montmartre by an unknown assailant. He is rescued by Major Jack Falconbridge, a private detective from New York who reveals himself to work tracking international criminals. Falconbridge, who had observed Isaacstein at the Prefecture, now takes interest in the connection between the merchant and Brookton's mysterious reappearance.