Sworn Enemy (1936)

Hank Sherman is a law student who stumbles into a job as a chauffeur for a wealthy businessman and, in the process, falls in love with his boss' beautiful assistant Margaret. His job becomes significantly harder, however, after his boss and his brother Steve, manager of a boxer named Steamer Krupp, are murdered, and he volunteers in the effort to catch the mobsters who did it. In order to get closer to head man Joe Emerald, Hank takes over Steamer's career. Steamer's subsequent success naturally catches the interest of Emerald, who muscles his way in. Hank and Emerald eventually reach a deal regarding Steamer, and Hank gains entry into Emerald's world. Once inside, Sherman works with the police to avenge the deaths of those near and dear to him.