At a railroad construction crew outside Junction City, Colorado, Grant McLaine, a former trouble-shooter who was dismissed five years earlier for allowing notorious robber The Utica Kid to escape, earns money by playing his accordion. After his former friend, railroad executive Ben Kimball, asks Grant to come to Junction City to discuss Whitey Harbin, the leader of a gang of outlaws that has been stealing the company payroll, Grant sets out on the trail. There, he meets Miss Vittle, a rough mining cook who reveals that a group of gold miners carved a hidden passage through the mountain that now serves as a shortcut into Junction City. Grant gratefully travels through the shaft and, once on the other side, saves young Joey Adams from Concho, a man who has been pursuing him. Grant offers Joey a ride into town, but the boy politely refuses, so Grant enters town alone. He stops at the city restaurant counter where Charlotte “Charlie” Drew, the sweet-natured girl friend of The Utica Kid, works as a server, and she reluctantly informs Grant, who suspects that The Utica Kid is behind the recent robberies, that the outlaw has left town. Grant then visits Ben’s office, where he is forced to be civil to both Jeff Kurth, the man who fired him, and Ben’s wife Verna, who failed to stand by Grant, her then-suitor, when he was accused of abetting The Utica Kid. Ben and Verna now urge Grant to accept a job transporting the $10,000 payroll back to the railroad camp, stating that no one would suspect that the company would trust him with the money. Jeff announces that he and his guards will hide in a railroad car behind Grant to keep an eye on him, and in response, Grant states that he will only take the assignment if he is given Jeff’s job. Ben agrees, and outside, Verna kisses Grant for luck. Meanwhile, Joey enters town and, after convincing Charlie to let him help sell sandwiches to the railroad workers at the end of the line, boards the same train as Grant. While Joey sits next to Grant, Charlie sees Ben and Verna secretly board a private car on the same train, and follows them on Grant’s horse. At the same time, Ben’s accountant, Will Renner, who has missed the train, hires Miss Vittle to lead him through the mine shaft so he can catch the train farther down the line. On the train, Joey admits to Grant that he joined Whitey’s gang under the tutelage of The Utica Kid, but after he tried to run away, Whitey sent Concho after him to keep him quiet. Just then, Concho hops into their car, but keeps his distance after he recognizes Grant. Watching the train from the hills is The Utica Kid, whose amiable disposition belies a quick mind and an even quicker gun. His alliance with the hot-tempered Whitey is an uneasy one, but Whitey retains control of the gang, and now, although The Utica Kid suggests that they let this payroll go through, Whitey refuses. The gang quickly derails the train and detaches the car containing Jeff and the guards, prompting Ben to suspect that Grant tipped them off. As Whitey futiley searches for the payroll, Grant and Joey hide the money in a shoebox. Frustrated, Whitey boards Ben’s car and abducts a calm Verna, explaining that he will meet Ben later to trade her for the money. As the gang leaves, The Utica Kid takes Joey, who still holds the shoebox, with him, and Concho throws Grant over a cliff. Grant soon revives, however, and staggers back into town with his accordion. That night, the gang returns to their hideout, where Whitey guards Verna possessively, ignoring The Utica Kid’s warning that she is trying to provoke the men into fighting over her. Charlie rides to the hideout in secret, and is almost attacked by gang member Howdy Sloden when Grant arrives and knocks him out. After chastising Charlie for her attachment to The Utica Kid, Grant strides into the hideout and asks to join the gang, forcing The Utica Kid to admit that his real name is Lee McLaine, and that Grant is his older brother. Thrilled by the rivalry, Whitey welcomes Grant, but Concho challenges Grant to a duel, which Grant wins easily. Grant then calls his brother outside, where he urges him to remember their parents’ teachings and reform himself, but The Utica Kid, resentful that he has always been in Grant’s shadow, refuses. Grant warns that if he leaves he will take the money, Joey and Verna with him, but The Utica Kid turns away and, spotting Charlie, promises to marry her. She, however, has overheard his discussion with Grant, and now rejects his proposal. When he reenters the hideout, Grant is playing a song from their childhood, and despite himself, The Utica Kid is moved by a memory of their father. Just then, Renner, who has been secretly informing Whitey about the payrolls, arrives and reveals that Grant was the one carrying the $10,000. Grant throws his accordion at the light and, under the cover of darkness, escapes outside in a burst of gunfire. He, Verna and Charlie race to the nearby mines with the gang in pursuit. Grant sends Verna through the shortcut to the end of the line, but Charlie refuses to leave him, and together they fight off the gang. When Grant is cornered and Joey runs to help him, Whitey shoots and wounds Joey, after which The Utica Kid joins Grant in fighting Whitey. Together, the brothers kill all of the gang except Whitey, who sneaks up behind them and shoots The Utica Kid. With only one bullet left, Grant kills Whitey, and holds his brother while he dies. Later, Charlie and Joey help him bury The Utica Kid, and then return the payroll to the railroad camp. There, Verna has told the story to Ben, and he and Jeff gratefully welcome Grant back to work. After shaking Jeff’s hand, Grant takes Charlie’s, and together they join the crew.