James Cagney gives a gritty performance as the little guy battling big league corruption. When he takes over for the former deputy of the Bureau of Weights and Measures, Johnny Cave (Cagney) butts heads with high-ranking city official Marty Cavanaugh, who is corrupt as the day is long. Johnny is framed by Cavanaugh's office when he tries to turn in a crooked philanthropist. His evidence is stolen and the case falls apart. He finds help in the nick of time from his fiancee Janet (Mae Clarke, recipient of the famous grapefruit in the face in Public Enemy) who aids his attempt to retrieve the incriminating papers from the mugs and save his skin in the process. With his patented tough guy veneer and fists swinging, Cagney roughhouses his way through this first of two screen appearances for Grand National Pictures.

Ex-prizefighter Johnny Cave (James Cagney) exposes corrupt officials and racketeers while working for the Department of Weights and Measures. Eventually the boisterous Cave has to face a corrupt alderman who put the last Inspector in the hospital.