Choya, Alan Ladd, a gunfighter on the run, is tracked to the mountains by two cowboys — Robert Keith as Leffingwell and John Berkes as Tattoo — who force him into a scheme to bilk a wealthy rancher named Lavery. The plan hinges on a distinctive tattoo on Choya’s shoulder, and when Tattoo actually creates the mark, Leffingwell shoots him in the back, leaving Choya to carry out the rest of the ruse with a shaken conscience.
Choya rides to Lavery's Bar M ranch and asks foreman Ransom for a job, hoping to lay low. Lavery, [Charles Bickford], arrives with his daughter Ruth [Mona Freeman], and they hire him on the spot. Ruth shares a painful memory: years ago, her five-year-old brother was kidnapped and never found. Lavery’s keen eye notices the tattoo on Choya and is stunned because his long-lost son carried a similar mark. Choya tells a story of a childhood memory to convince them—he subtly suggests he could be Richard, Jr., the missing son—and the couple begins to believe him.
Leffingwell arrives at the ranch and is unexpectedly hired, seeding the plan with a new motive: to kill Lavery so that Choya can inherit the Bar M. A guilty Choya offers a different option for escape: steal Lavery’s stock during the cattle roundup. Ruth rides along, and as Choya grows more attached to her, he double-crosses Leffingwell by directing the cattle money into Lavery’s El Paso bank account. In the process, Choya discovers Leffingwell was the mastermind behind the kidnap—only to learn that Rubriz, a Mexican bandit, has actually raised the boy. Choya confesses the truth to Ruth and leaves the ranch, torn between loyalty and the safer path he’s chosen.
Crossing the border, Choya uncovers a staggering truth: Lavery’s son was raised by Rubriz as Tonio. To reunite Tonio with his rightful family, Choya convinces Tonio to return home. Rubriz, who has treated Tonio as his own, dispatches his men after them, and Tonio is wounded in the pursuit. Leffingwell follows, but he is killed in a stampede, removing the immediate threat. Choya and Tonio find themselves cornered on the Texas side of the Rio Grande, only to be rescued at the last moment by Lavery and Ransom.
When Rubriz and his men reach the ranch to finish the job, Choya disarms Rubriz and persuades him that Tonio did not betray him. Rubriz has a change of heart and tells Lavery that Tonio should stay with the Lavery family until he recovers from his wound, with the understanding that Rubriz can visit anytime. With the plan shifted and Tonio safe, Choya contemplates riding away for good, but Ruth follows and asserts that she’ll go with him. They ride off together, and as they reach the horizon, they share a kiss, while Choya heads back toward the ranch house with a sense of uncertain hope.
