Phoenix cop Ben Shockley is well on his way to becoming a derelict when he is assigned to transport a witness named Gus Mally from Vegas. Mally turns out to be a belligerent prostitute with mob ties and incriminating information regarding a high-placed figure.
Young Treasury Agent Elliot Ness arrives in Chicago and is determined to take down Al Capone, but it's not going to be easy because Capone has the police in his pocket. Ness meets Jimmy Malone, a veteran patrolman and probably the most honorable one on the force. He asks Malone to help him get Capone, but Malone warns him that if he goes after Capone, he is going to war.