Young Treasury Agent Eliot 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 Jim 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.

A US Treasury Agent finds himself in opposition with his fellow agents who are involved in gun running.

Barstow and Stevens are forcing the local printer to print fake silver certificates which they then sell. Treasury Agents Chick Weaver and Throckmorton Snodgrass arrive working under cover. But when Chick's true identity as an Agent is revealed, Barstow sends his henchmen to finish him off.

Cowboy T-man, Rex Allen, and his partner, Homer Oglethorpe (Buddy Ebsen), go undercover to track down some gold smugglers.

Using marked bills, Steve is looking for the supposedly dead Henry Hardison. Coming to Bonanza Town he gets a job with the town boss Crag Bozeman and gets paid with marked bills. He suspects Hardison is Boseman's boss and he is right as Hardison and his men are now planning to get rid of both him and the Durango kid.