Key lieutenant of South Side Chicago crime boss Johnny Lovo (Osgood Perkins), Tony Camonte (Paul Muni) is an ambitious and reckless gangster who ignores warnings not to mess with Irish gangs on the North Side. When the North Side retaliates, Tony essentially massacres them, leaving him on top of the world. Worried about Tony's overconfidence, however, Johnny orders him killed, but this also backfires, and Tony finds himself even closer to becoming king of the city.