Young Treasury Agent Elliot Ness arrives at Chicago and is determined to shoot down Al Capone, but it's not going to be easy because Capone has got the authorities at his pocket. Ness matches a veteran patrolman Jimmy Malone and probably the most honorable person on the force. He inquires Malone that will help him buy Capone, but Malone warns him that if he goes later Capone, he's going to war.