Young drifter Jess Harker has settled in the small town of Red Rock, where he drives a sedate mail route on the stagecoach line supervised by Luke Bowen, and dreams of being a real driver alongside his hero, stagecoach guard Race Crim. Race's best friend, Sheriff Tom Davisson, disapproves of Race's reliance on "six-gun law," and tries to impart his own even-temperedness to the impetuous Jess. Hoping to find a driving job farther west, Jess tells his girl friend, Kathy Riley, that he is leaving town. Desperate for Jess to stay, Kathy pleads with Race to ask Bowen to hire Jess for the main line. Race persuades Bowen to let Jess drive, as long as both Race and guard Uncle Ben Nunan accompany him. Along with a male passenger and Waco, a saloon girl who is Race's girl friend, the stage will be carrying $27,000 in gold dust, and Bowen lectures Jess that the safety of his passengers and cargo come first. To celebrate, Race buys Jess a whip with a silver handle, and Jess reaches the relay station at Buffalo Gap right on time. When they arrive, however, Race is suspicious of the silence, and orders Jess to take the stage out. Jess ignores him though, and when outlaw Slater and his men open fire on the stage, Jess again ignores Race and stays behind to help him. Jess is wounded during the shootout, and Uncle Ben and both passengers are killed before Slater and three of his men escape with the gold. Race insists that Jess continue to Silver City, while he pursues the bandits. In Silver City, Jess's wound is tended to and news of the attack is telegraphed to Bowen, who orders Jess to return immediately. Jess instead joins Tom's posse, and during their pursuit, they discover that Race has killed two of the bandits. Tom is infuriated by Race's vigilantism, and when they find one of the bandits, Hank, at the same time, Tom confronts Race and orders that the man be taken alive. When Hank reveals that Slater has headed north, Race confides in Tom that he blames himself for Waco's death and leaves in pursuit. Tom maintains that it more prudent to wait until Slater shows himself, and Jess accompanies him as he escorts his prisoner to jail. In Red Rock, Bowen fires Jess for disobeying Race's orders, and the despondent Jess, finally accepting responsibilty for his mistakes, asks Tom for a chance to atone. Tom agrees, but warns Jess that being a deputy will require patience and discipline. Later, a rancher informs Tom that Slater has left his hideout to head farther north, and as Tom and Jess begin their manhunt, they realize that Race has also picked up Slater's trail. Race, Tom and Jess find Slater at the same time, and Race shoots and wounds Slater, although Tom pulls a gun on him to prevent him from killing the outlaw. Race is infuriated but nonetheless accompanies Tom and Jess as they return to Red Rock. There, the angry citizens want to lynch Slater, but Tom promises that Judge Lucius Webb will be arriving in the morning, and Race reluctantly agrees to wait for the trial. When Tom incarcerates Slater, however, he informs Jess that Webb is not due to arrive soon, and that he was stalling for time. While Race and his friends drink in the saloon, Bowen telegraphs the judge, requesting that he come to Red Rock immediately. Webb initially demurs, and one of the telegraphers reports his decision to Race. While the men urge Race to lead them in lynching Slater, Tom decides to appeal to the judge personally and leaves the jail, after instructing Jess not to let anyone in. Race organizes the men and captures Tom, and although Tom warns Race that Jess will stand up to him, Race assumes that the youth will do as he tells him. When Race and the mob approach the jail, however, Jess refuses to open the locked doors and prepares to shoot as the men chop at the doors with axes. Meanwhile, Bowen finds Tom and frees him, but the men arrive after Jess has been forced to shoot Race for continuing to advance toward Slater despite Jess's warning to stop. Tom disperses the mob, then sends for a doctor for Race. Sickened at injuring his hero, Jess prepares to leave town, but Tom urges him to visit Race before he goes. Race, who has forgiven Jess, teases him about being able to drive straighter than he can shoot, and Jess cheerfully replies that it is so because Race only taught him to drive. Later, as Jess, who has been re-hired by Bowen as a driver, and his new bride Kathy are about to leave on their honeymoon, Tom and Race stand on a balcony to bid them farewell, and Race throws Jess his silver whip.