During the American Civil War, renegade Confederate officer William Clark Quantrill and his raiders unleash a savage attack against the city of Lawrence, Kansas. Jeff Travis, serving as an advance spy for Quantrill, is dismayed to see the city brutally pillaged and its citizens willfully murdered. When Jeff learns Quantrill intends to keep the spoils instead of using them for the Southern cause, he flees, enlisting in the Confederate Army, where he serves out the remaining war years. After the war, Jeff works on a river boat with his longtime girl friend, card sharp Josie Sullivan. On one trip, some men confront Jeff about his past connection with Quantrill, and with the help of a stranger, Jeff escapes. Josie warns Jeff that he is wanted for the Lawrence raid and on her advice, Jeff jumps ship and heads West. Some weeks later, Jeff arrives in Prescott, Arizona as a gang of thieves, headed by sophisticate Jules Mourret, makes an unsuccessful attempt to hold up a Conroy Stage Line coach, run by Jason Conroy and his daughter Shelby. Conroy avoided being robbed by hiding the gold in a different location for each trip, never revealing the hiding place to the driver. Jeff arranges to meet Mourret, whom he recognizes as the stranger who helped him escape the river boat. Impressed by Jeff's work for Quantrill, Mourret offers him a job spying on the Conroys to discover how large amounts of gold are being safely transported. Jeff agrees, assuming the identity of Mark Stone, an insurance detective requested by the Conroys, and informs them he will masquerade as a stage guard to protect the gold. The next day the Conroy stage arrives carrying Josie and Mexican bandit leader Degas, Mourret's rival, who also anticipates stealing the line's gold transports. Shortly afterward, an attempt is made to stop the stage by Degas' and Mourret's gangs, but Jeff gets the stage away safely. When Mourret angrily chastises him later, Jeff explains that he has learned that the next stage will be carrying $25,000 and thus will be a more important robbery. When that stage is attacked and the driver, Shelby's uncle Jake, is tortured and killed in an attempt to find the gold, Jeff guiltily reconsiders his association with Mourret. After Shelby tells Jeff that she and her father are reluctantly closing down the line to prevent more killings, he convinces them to keep the line going a little longer. Jeff then informs Mourret that the next stage gold shipment is to be $100,000 and says the Conroys have assigned him to drive. Mourret reveals that one of his men is missing and he suspects the man is being held by Degas. Jeff goes to Degas' hideout, where he finds Mourret's man, but intending to set a trap for Degas, tells him about the $100,000 transport and offers to kill Mourret for a third of the gold. The next day, Mourret sends one of his henchmen, Dan Kurth, to ride with Jeff on the stage, which is ambushed by both Degas and Mourret. Jeff pushes Kurth off the stage, then disappears as the gangs confront one another and Mourret ends up killing Degas. Jeff returns the gold to the Conroys, then in his hotel room confesses to Josie his distress about Jake's brutal murder and his life as an outlaw. Josie hesitantly admits that to keep Jeff dependent upon her, she lied to him about his being wanted for his association with Quantrill. Moments after Josie departs, Kurth and another Mourret henchman, Bull Slager, break into Jeff's room, demanding to know the location of the gold. After tying up Jeff, Kurth departs to get Mourret, and Jeff convinces Slager he will split the gold with him. When Slager loosens the ropes, Jeff breaks free and escapes. Jeff then runs into Kurth and kills him. Slager reports to Mourret at the saloon, and Mourret rouses the townsmen by revealing Jeff's connection with the infamous Quantrill. Josie tries to enlist the sheriff's help, but only finds his deputy, who refuses to get involved. Meanwhile, Jeff explains his entire past to the Conroys and, warned by Josie, evades Mourret and the vigilante group. Jeff remains missing through the night, and the next day Mourret grows anxious upon discovering the townspeople have lost interest in Jeff's capture. Soon after, Jeff arrives at the saloon to challenge Mourret and Slager. When a fight breaks out between the men, Josie throws a kerosene lamp at Mourret, and the saloon bursts into flames. Jeff shoots Slager and escapes as the burning ceiling collapses on Mourret. Afterward, Shelby asks Jeff to remain in Prescott, but he decides to start a new life with Josie in California.
