U.S. Marshals "Nevada" Jack McKenzie and "Sandy" Hopkins go undercover to bust a gang of stagecoach robbers in this vintage Western serial. Nevada infiltrates the gang, while Sandy works as a cobbler in town, keeping an ear open for local gossip as they try to flush out the inside man tipping off the crooks.

The Pony Express is finished as the Post Office plans to award the mail contract to a stage line. Bill and his father put in a bid for the mail, however there are three bids close together. The officials will run a race to pick the winner, and the Banton Brothers sabotage Bill's stage. Mary still believes in Bill until they try to get rid of him by holding up the regular stage with his well-known horse. Bill needs proof to clear himself and expose the bad guys.

Twelve renegades dressed as Indians kill the parents of two brothers. The brothers who have similar birth marks then separate. Ten years later a man known as the Rawhide Terror is murdering the renegades who are now town citizens. Everyone is after the Rawhide Terror and the two brothers are destined to meet again.