Holdups of his stagecoach line are threatening to put John Watson out of business, as the lucrative mail contract he needs to obtain is dependent upon the line maintaining its regular run. Baxter, a crooked lawyer who works for "The Boss," is responsible for the robberies and tells his head gunman, Stocker, that Watson has sold his ranch to keep the stages running and is about to ride out to meet his son and daughter, Bob and Margie, who are bringing the money from the sale. Baxter orders Stocker to "take care" of them and steal the money. U.S. Marshal Cheyenne Davis and his deputy, "Fuzzy" Q. Jones, are heading to Mesa City to investigate the robberies on Watson's line when Cheyenne sees Watson being pursued by two gunmen. Cheyenne arrives arrives too late to stop them from shooting Watson, but before he dies, Watson tells Cheyenne that Bob and Margie are waiting for him at Eagle Pass. After Cheyenne and Fuzzy rescue Bob and Margie from three other gunmen, Cheyenne has to break the news of their father's death to them. Although Baxter later urges them to sell out, Bob and Margie decide to try to keep the line going and introduce Cheyenne to Baxter as their new business manager. At the post office, Tom Padgett, the wheelchair-bound postmaster, tells Cheyenne that he hopes the younger Watsons can keep the line in business. At Stocker's saloon, Bob spots Ed Williams and Jim, the gunmen who attacked him, and challenges them. Ed draws his gun on Bob but Cheyenne arrives in time to knock the weapon out of his hand with his whip. A fistfight ensues, and Cheyenne and Bob best the outlaws. Cheyenne and Fuzzy later trail several gunmen to a meeting with Baxter, who tells them that he has found out that Cheyenne is a U.S. Marshal and orders them to get rid of him. When Fuzzy's gun goes off accidentally, he and Cheyenne are spotted and chased by the gang but manage to lose them. Cheyenne then goes after the gun-toting Baxter and defeats him with his whip. Just as Baxter is about to reveal who "The Boss" is, he is killed by an unseen gunman. Later, Margie receives a letter from a post office inspector, who has arrived in Ranchito, saying that if the stage makes the run that day and brings him back to Mesa City, she will be awarded the mail contract. Cheyenne leaves Fuzzy in town to keep an eye on things there while he rides along with the stage, on which Margie will be the contractually required passenger. Four masked gunmen attack the stage before it reaches Ranchito and shoot Pete, the driver, who falls off, causing the horses to rush onward with Margie still on board. The horses eventually stop, and after Cheyenne and Margie are shot at by a fleeing gunman, Cheyenne discovers that the shooter gunman has lost the heel of one boot. Cheyenne and Margie continue on to Ranchito and then back to Mesa City, where Margie and the postal inspector arrange to finalize the contract. Fuzzy tells Cheyenne that, while he was gone, the post office was closed for an hour, and a suspicious Cheyenne goes to talk with Padgett. When he notices a heel missing from one of Padgett's boots, Cheyenne accuses him of faking his paralysis and of being the brains behind the attacks on the stage line. Padgett jumps Cheyenne and escapes on horseback. After a long chase, Cheyenne knocks him off his horse, and the two men fight until Padgett is finally vanquished. Back in Mesa City, Cheyenne jails all the gunmen, and is thanked by Margie and Bob. Cheyenne then moves on to a new assignment, leaving Fuzzy to be appointed the new sheriff of Mesa City.
