Shortly after the end of the Civil War, the Canfield brothers, Britt, Tom, Clint and Terry, leave the ruins of their Virginia plantation and ride northwest in search of new lives. In the saloon of a small Missouri town, two drunken Union soldiers taunt them. Despite oldest brother Britt's efforts to maintain calm, one of the soldiers draws and fires and is killed in self-defense by Tom and Clint. Knowing they stand no chance for a fair trial, the Canfields flee, jumping a westbound train, filled with men seeking work on the new Santa Fe railroad line. Later, when the railroad representative, Col. Holliday, swears men in for jobs, Britt accepts, but his brothers refuse to take the oath of loyalty to the Union. Holliday's assistant, Dave Baxter, recognizes Britt as a former member of a Confederate guerrilla band, but, despite having been with the Union forces, Dave is pleased to hire Britt under an assumed name. Meanwhile, casino owner Cole Sanders approaches Tom, Clint and Terry, promising them work. Britt works diligently as the head of a railroad gang and reports to paymaster Judith Chandler, who knows his identity and is cool to him because her husband was killed in a raid Britt led during the war. Dave is impressed by Britt's sure way with the men, trespassers and Indians, and promotes him to his assistant. Britt soon realizes that a mobile gambling saloon has been trailing the railroad outfit, swindling the workers out of their pay. Britt confronts the setup, only to discover his brothers are working for Sanders. Britt warns Sanders to keep away from the crew and demands that his brothers leave. Later, however, Dave and Britt find that Sanders has interfered with the company's surveyor, keeping the company from receiving a necessary government land grant, but Britt's quick action saves the grant. When the railroad dedicates the new line in Dodge City, Britt is pleased to see his brothers. Terry introduces Britt to his new young wife, Ella Sue, and the brothers declare their intention to work honestly to make money to return to Virginia. Soon after, however, the Santa Fe train in which Britt is riding is held up by masked bandits and a trainman is killed. Britt recognizes his brothers and confronts them. Tom, who has been wounded, admits they still work for Sanders. Marshal Bat Masterson and a wounded engineer then arrive to accuse Terry of being one of the bandits. Terry is arrested just before Tom dies. Meanwhile, Judith finds a wanted poster for the Canfields for the death of the soldier in Missouri and tells Britt. Yet when the rail line is suddenly confronted by competition from another line, Judith encourages Britt to remain loyal to the company. Britt proves the robbery witness is unreliable and once Terry is freed, departs to beat the challenging railroad line to a crucial mountain pass. Later, Sanders discovers that the payroll train arrives that night and plans another holdup with Clint and Terry. Judith worries about a robbery, but Dave assures her Masterson has set a trap to apprehend the bandits. When Britt finds out, he confides in Clint, unaware that Sanders is eavesdropping. Britt promises his brothers he will return to Virginia with them if they call off the heist and they agree. As Britt goes to resign from the rail line, Sanders blackmails Clint and Terry into robbing the train depot safe, threatening to reveal Britt's identity. After the robbery, Britt finds Ella Sue and forces her to reveal Sanders' plans. Masterson and Dave go after Sanders. Britt confesses his identity to the marshal and insists on going along. Confronting Sanders and the Canfields at another railroad junction, Britt tries to get them to give themselves up. When Sanders fires upon Britt, Terry and Clint interfere, only to be shot by Sanders, who then leaps aboard the incoming train with his henchman. Britt follows and after a harrowing fight aboard the speeding train, Britt kills both men. When the Santa Fe line opens in Santa Fe, Judith learns from Dave that Britt is working with the company on another line in Nevada, and hastens to join him.