Le mystère du dancing

Gangster Jim Boyd serves a 15-year prison term when Hardy, a rival crook, doublecrosses him. On his release from prison, Boyd seeks out Hardy in Chicago, where he runs a cafe and bootleg operation. He makes the acquaintance of Mona Gale, a dancer in Hardy's cafe who is engaged to marry Jack Waring, the orchestra leader. Unaware that Mona is his daughter, Boyd shoots Hardy in a brawl and leaves behind evidence implicating Waring as the murderer. After Hardy's death, Mona joins Boyd's gang to gather evidence proving her fiancé's innocence. The gang members discover that Mona has dealings with the police, and they begin to torture her. Having learned of Mona's relationship to him at the last minute, Boyd arrives at the gang's hideout in time to save her. He confesses to killing Hardy before he dies from a wound inflicted by one of his own gang, thus freeing Waring to marry Mona.