In Arizona in 1877, ranchers are being driven out by the Law and Order League, an illegal organization with ties to local law enforcement. As they threaten a lady rancher, Jane Withersteen, and her ranch hands, a man named Lassiter comes to the rescue. To show her gratitude, Jane asks Lassiter to stay for dinner, at which time he tells her that he has come in search of the man who killed his sister, Millie Erne, and abducted her baby daughter. Jane, who lost her father in a shootout, hates gunfighting and refuses to tell Lassiter the man’s name. Meanwhile, Tull, the leader of the Law and Order League, has reported Lassiter’s arrival to his superior, Judge Dyer. Dyer is determined to take Jane’s land, but one of the gang members, Oldring, defends her. That night, out on the range, some men from the Law and Order League are spotted with a gunfighter known as the “Masked Rider.” The next day, as Lassiter is reciting a nursery rhyme to Jane’s adopted daughter Fay, Judkins, one of Jane’s ranch hands, reports that rustlers are stampeding her cattle. Through a daring maneuver, Lassiter is able to save the stampeding herd from being driven over the cliff into Devil’s Canyon, but he loses his horse and cannot follow the herd. With the help of Venters, another rancher whose land the Law and Order League took over, Lassiter discovers the cattle being herded through a secret passageway masked by a waterfall. Lassiter follows the herd and, once inside the hidden valley, sees Oldring talking to a young woman named Bess. Lassiter tries to follow her, but runs across the Masked Rider. A gunfight ensues during which the Masked Rider is hit, and Lassiter discovers that the Masked Rider is actually Bess in disguise. Lassiter and Venters take her to a hideaway on a cliff, and in her delirium, Bess sings the same nursery rhyme that Lassiter sang to Fay earlier. Lassiter leaves Venters with Bess and goes to get medical supplies, but he is ambushed and wounded. Lassiter returns to the ranch, and when he tries to stop Tull from harassing Jane, Tull pulls a gun and threatens to shoot him. Jane overcomes her dislike of guns and grabs Lassiter’s to scare Tull away. A week later, Lassiter, recovered from his wounds, goes to the hiding place to find that Venters and Bess have fallen in love. Lassiter finds Oldring and forces him to reveal that Judge Dyer was responsible for Millie’s death. Oldring confirms that Bess is Millie’s daughter. To prove to Jane that he respects her hatred of gunfighting, Lassiter offers to leave his gun behind, but just then, some men from the gang ride up to the ranch and abduct Fay. Lassiter follows them to Dyer’s courtroom, where Dyer is conducting a hearing to determine with whom Fay will live. During a shootout, Lassiter kills Dyer. Lassiter returns Fay to Jane, with Tull and his men in pursuit, and Jane tells Lassister that she wants to escape with him. They set the ranch on fire and go to the cliff, where Lassiter insists that Bess and Venters leave immediately. Once Bess and Venters are safely out of the valley, Jane confesses her love for Lassiter, and he tips a huge boulder, carved by the ancient cliff-dwellers to seal off the valley against their enemies, off its perch, to protect himself, Jane and Fay from their pursuers. The three are then locked inside the valley. More on Wikipedia or Mubi
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