In July 1881, Billy the Kid is visiting the home of José and Rosa Gonzales when he is shot and killed by Pat Garrett. Fifteen years later, on the outskirts of Baldwin City, four outlaws attempt to hold up a stagecoach carrying local banker Jim Thorn, but the attack is foiled by lone gunman Jack Garrett. When Fuzzy, the driver, eventually brings the stage into town, Thorn is met by his niece Norma. Meanwhile, the outlaws are upbraided by their boss, land speculator Cy Shaeffer. Intent on foreclosing on numerous ranchers who own valuable land, Shaeffer tells his men that he has sent for Clem Yantis and his gang as reinforcements. Jack then reveals to Thorn that he is a federal marshal assigned to ensure that railroad interests are protected and is making arrangements for Thorn's bank to handle the cash involved in the railroad's expansion to Baldwin City. Fuzzy, who is also the town's sheriff, learns that the Yantis gang, which once rode with Billy the Kid, is in the area. Later, after Jack informs Thorn that a shipment of cash is coming in by prairie schooner, Yantis and his men plot to hold it up, but Jack and Fuzzy intercept the shipment and the gang abandons the plan. Having recognized Thorn as Billy the Kid, Yantis pays a visit to Thorn's office and draws a gun on him, telling him that Billy's son Colt is one of his gang. He then blackmails Thorn into delivering railroad funds directly to him. After Jack and Fuzzy head out to a pass in the prairie schooner that is supposedly carrying cash, Norma draws a gun on Thorn as he attempts to put money in a safe and admits that she is in cahoots with Shaeffer and Yantis. However, Colt enters and disarms her. As Jack and Fuzzy traverse the pass, they are held up by Shaeffer's gang, but several of Jack's friends pop out of the schooner and return fire. Thorn rides up and battles alongside Jack, who reveals that he knows Thorn's true identity. After Colt shoots Yantis, Jack chases Shaeffer and eventually trips him with his whip. They fight on top of a promontory and Shaeffer falls to his death. Later, Thorn explains that Norma was his niece by adoption and that Colt had offered to help him by joining Shaeffer's gang. Thorn then tells Jack what happened at the Gonzales home fifteen years earlier: Pat Garrett, who had learned about the plan to trap him, fired three wild shots at Billy, who feigned death. Pat then told the accompanying sheriff that Billy was dead. However, one of the bullets had killed the Gonzales' son Sanchos, who was later dressed in Billy's clothes and officially identified as him. Since then, Billy has been sending money to the Gonzales family. Jack assures Thorn that he thinks that because of his long record as an honest banker, the governor will probably be lenient with him.
