A bank is robbed and a teller killed. The four brothers responsible knock out Bronco and make it look like he was involved. He is arrested but escapes when lynch talk gets out of control and heads with the sheriff to find the real robbers.
Bronco rides into Peaceful to see his Army friend Marshal Durrock and his daughter Molly. He finds himself the acting Marshal when the Tilsey gang kidnaps Molly threatening to kill her unless they have free reign to steal a gold shipment.
Bronco has been requested to transport a prisoner to Santa Fe for trial for robbery and murder while a decoy goes on the stage. He loses sealed instructions for an emergency which occurs when a victim's relatives attack them.
Bronco is hunting meat for the railroad in Montana working for Henry Paddock. After a fight over a bear with Theodore Roosevelt, they come to respect each other. Bronco soon realizes Roosevelt is right that his bosses are up to something.
Deputy U.S. Marshal Bronco is asked to go with two marshals to Canada to identify a wanted man - his commanding officer in the war. In Canada they meet with the RCMP who help find the man. However, questions arise about his two partners.
Bronco stops the lynching of a friend who went from gunfighter to minister. The money he raised for a new church was stolen so the parishioners with some encouragement think he stole it. Bronco soon discovers who he thinks really did it.
Bronco finds the owners of the Rocking Chair ranch, Gil Groves and Petrie Munger, have split the ranch allowing a feud to develop. Munger has hired a sadistic gunman, who beats Bronco and Groves' foreman leaving them in the desert to die.
Sheriff Bronco welcomes his pretty young cousin Amanda from Atlanta hoping to find more excitement. Unfortunately one of the things she finds exciting is a young gunman who has his own devious plans for the town's upcoming social event.
Bronco and actor Edwin Booth, brother of President Lincoln's assassin, work undercover by pretending to be hostile to America so as to infiltrate a group that is plotting to overthrow the government at the request of President Grant.
Bronco hires on as a guide to three men and a woman who claim to be starting a business in another town. Actually they are a gang of robbers who have already killed one Pinkerton agent, and are now being pursued by another.
Bronco is assigned to keep the peace between feuding outlaws Butch Cassidy and Billy Doolin as they - and their gangs - visit the town of Painted Rock for the wedding of Cassidy's niece and Doolin's brother but others take advantage.
Bronco and hard-drinking Irishman Terrence Harrigan are fired after the wagon they were guarding is attacked, drivers killed and the gold shipment stolen. Both Harrigan and Bronco decide to fight the gang responsible by infiltrating it.