A young cowboy and a Mexican girl run from a ruthless criminal.

After rancher Johnny Jordan is shot in the back and killed, his brother and partner Trace becomes determined to bring the guilty party to justice. Evidence found near Johnny's body reveals that several men were present during his murder: one with a limp, one with elaborate spurs, and one who smoked a certain type of cigarette. Trace's friend Miguel identifies the men as toughs who work for Joe Sutton, a powerful rancher who wants no other settlers on the range. Trace rides into the town of Esperanza, and before he climbs the wall into Sutton's ranch, he notices that several of the horses on the property bear his brother's brand. Now fully convinced that Sutton's men committed the crime, Trace draws his gun and confronts the rancher. Sutton dismisses the accusation, but when Trace threatens to take his evidence to the U.S. Cavalry at Fort Stockwell, the rancher pulls out his own gun. Trace shoots Sutton in self-defense and then escapes over the wall, whereupon the wounded Sutton angrily orders his son Jack and foreman, Ben Hindeman, to "finish the job." The young cowboy, who also was shot, rides out of town but soon loses consciousness. He is found by Maria Cristina Colton, a spirited young woman who keeps a small herd of sheep with her younger brother Vicente and her lazy uncle Perico. Maria is drawn to Trace because he reminds her of her father, a Yankee rancher who married a Mexican woman and was killed while trying to stand up to Sutton. Maria hides Trace in an abandoned mine, and while he recovers from his wound, she creates a false trail to confuse Jacob Lantz, a tracker of mixed Dutch and Ute blood, who is reluctantly working for Sutton. This temporarily slows the scout down, but when Maria realizes that Lantz and the other men in the tracking party are headed toward the mine, she urges Trace to escape and meet her later at an isolated ranch. Furious that Trace has eluded them, Jack shoots Ben and takes control of the gang. Maria brews some coffee for the men, lacing it liberally with jimson weed, and as Jack tries to force Maria to disclose Trace's whereabouts, he and most of the other men fall ill. Fearing for his sister's life, young Vicente reveals Trace's location, and the poisoned coffee buys Maria only a little time to ride ahead and meet Trace. At the ranch, Trace fights with and finally kills one of Sutton's men. Still just one step ahead of their pursuers, Trace and Maria cleverly conceal their tracks, and once, when Lantz has led the Sutton gang too close to them, Trace attracts a group of Indians to the area. The Indians attack Sutton's men, but three of the ruffians escape the battle and continue the chase. Maria and Trace arrive at an unfordable river, and while she takes the horse upstream, Trace hides in the rocks and shoots at his enemies. After killing one of them, Trace fights hand to hand with Jack, finally drowning him in the river. Lantz appears with his gun, but instead of shooting at Trace and Maria, he gives them directions to Fort Stockwell. He was ordered to find the escapees, Lantz explains, not kill them, and says that he looks forward to the Cavalry's visit to Sutton's ranch.