In the Arizona desert, gunmen Loder, Scully and Welton ambush a northbound stagecoach bearing a company payroll and a single passenger, Mr. Jefferson. In the gunfire, guard Ed Stewart is critically injured, but Sheriff Dan Harris, who has anticipated trouble and is riding as an additional guard, shoots and kills Welton. After Scully and Loder retreat, Dan and Bill, the driver, rush to the Eldorado Relay Station. On a southbound route, driver Sam and his guard Matt, encounter Juan Morales, a Mexican whose horse broke its leg on the trail. Taking the stranded Juan with them, the drivers continue to the relay station, which is run by Fred Moran and his weary wife Bessie. Helping Bessie is Cheel Palmer, to whom Juan quickly becomes attracted. As everyone anxiously watches, Jefferson, who appears to be a respectable businessman, offers to take the bullet out of Ed, thus saving his life. Afterward, Dan orders Matt and Sam to leave immediately for the town of Stockdale to alert his deputy and get a doctor for Ed. When the openly prejudiced Dan learns that Juan was picked up on the trail, he detains him at the station as a suspect. Juan indignantly denies being one of the gunmen, but circumstantial evidence convinces Dan to lock him in a bedroom. A romance swiftly develops between Juan and Cheel, who cannot believe Dan's accusation. After hearing Dan's vow that "someone" will hang if Ed dies, she doubts Juan's chance of being treated fairly and offers to lead him partway through the mountains on a path that will take him to Mexico. While Cheel saddles up horses for their escape, the eavesdropping Jefferson, who has heard their plans, confesses to Juan that the gunmen were working for him. By threatening to tell Dan that Juan is one of the gunmen, Jefferson forces Juan to agree to take the payroll money when he escapes and return it later to a designated rendezvous point. Feeling he has no choice, as Dan will believe Jefferson's word over his, Juan takes the money Jefferson has secretly taken from the strongbox. Jefferson distracts the men, so that Juan and Cheel can ride away, but Bessie soon discovers them and the money missing. Dan, Jefferson, Bill and Fred chase after the couple in the dark until the rocky hillsides prevent them from going farther. The next morning, Cheel shows Juan the way through the desert to Indian Pass, unaware of his plans to meet Jefferson. They agree that Cheel will return to the station, claiming that she was forced to ride along, and that Juan will send for her from Mexico. While she is preparing to leave, she discovers the money in Juan's saddlebag and, before Juan can explain, the disillusioned Cheel runs off and is surprised by the appearance of Loder and Scully, who capture her and Juan. After Juan explains that he is supposed to meet Jefferson, they take the money and are about to shoot the couple. When Jefferson, who is known to the gunmen as Pike, arrives, he assumes command, and the gang begins travelling, taking along the reluctant Juan and Cheel. Juan asks that Cheel be allowed to return home, but Jefferson says that she may only leave after Dan is off their trail. While blaming Scully and Loder for the botched robbery attempt, Jefferson praises Juan for smuggling out the money and gives him Welton's share, thus angering Loder and Scully. It also confirms to Cheel that Juan is part of the gang, despite his secret assurances that he will mail the money back to Dan. Seeing that Juan is disturbed by Cheel's rejection, Jefferson tells him that, like Dan, she is not giving him a chance. As they continue traveling, Jefferson, who has little regard for women, intervenes when Loder harasses Cheel, thus angering his lecherous henchman. By promising Scully both Jefferson and Juan's share of the money, Loder convinces him to assist in ambushing Jefferson. However, their scheme fails, and Jefferson shoots Scully in self-defense, leaving him for dead. Loder pretends to be innocent of the mutiny, but later, during a fierce thunderstorm, shoots Jefferson in the back, then forces himself on Cheel, who is setting up camp in a cave. Juan tries to rescue her, but cannot overcome Loder. Just then the wounded Jefferson enters the cave, and shoots and kills Loder. Jefferson then proclaims that Juan, for whom he has felt growing respect, is now his partner and gives him Loder's share of the loot. Early the next morning, Jefferson breaks camp and tells Juan they will leave the sleeping Cheel behind. When Juan refuses to leave her, Jefferson is offended and says that he is entitled to loyalty after the way he helped him. Claiming that he does not want to become another Loder, Juan says that he will mail all of the money back to Dan from Stockdale. They begin fighting and spill out of the campsite into the hills. While chasing Juan, Jefferson spots Dan and his men on a trail below and takes aim to shoot him, but Juan slips up from behind and shoots Jefferson first. Dan then reports to Juan that Scully, whom they found just before he died, confirmed that Juan was not involved in the robbery. However, Dan insists he must arrest Juan as a fugitive from the law and an accessory to the crime. Cheel, who had awakened and saw Juan stand up to Jefferson, vouches that Juan was forced into transporting the cash and that he planned to return it. After Juan hands over all of the loot, Dan concedes that Juan is not the type of man he thought and allows the couple to go on their way.
