Joe Gordon and his sister Judy arrive in Bowie, headed for the town of Gordonville, most of which is owned by their father, banker and rancher Paul Gordon. As they drive a buckboard to town, they are followed by two gunmen. However, U.S. Marshal Johnny Mack Brown is also on his way to Gordonville to meet Dusty Dekker, a retired marshal, and rescues Joe and Judy when the gunmen attack. Meanwhile, in Gordonville, at Dusty's livery stable, Paul tells him about a letter he has received from his wife Ann, whom he thought had died after she left him several years before. In the letter she announces that she is on her way to reunite with him and their children. Paul's conversation is overheard by Frank, his crooked ranch foreman, who then tells Jim Laren, the secret head of an outlaw gang that is planning to take over Gordonville, that Paul is about to leave the livery stable. Laren shoots and kills Paul, but Dusty spots him and chases after him on horseback, followed by Johnny. Frank tries to frame Dusty for Paul's death and, as Joe and Judy ride up, Alibi, the sheriff, is persuaded to create a posse to go after Dusty. However, Dusty has been taken prisoner by the gang and Johnny follows them to a shack where they intend to keep him, then rides back to tell Judy that he knows Dusty is innocent. At the shack, Dusty meets Ann Gordon, who is also a prisoner, and tells her that Paul is dead. After Judy tells Alibi that Dusty is not guilty, the undertaker hands Joe the letter from his mother and he and Judy are happy at the thought of reuniting with her. Ann, meanwhile, helps to untie Dusty and they both escape. Johnny sees this but is unaware that it has been engineered by Laren's men. Dusty and Ann arrive in town where Ann greets Joe but then accuses Dusty of kidnapping her and killing her husband. A mob intends to hang Dusty, but Johnny intervenes and they both ride off. Later, at the saloon, unaware that Johnny is a marshal, Laren tells him that he intends to go into partnership with Ann and run the town. However, Johnny shows Laren a photograph that he and Judy found of her father and mother, noting that the woman in the photo does not resemble Ann. Laren admits that the real Mrs. Gordon is dead and "Ann" is an impostor. He then confesses to having killed Paul and offers Johnny part of the deal, prompting Johnny to draw his gun and reveal that he is a lawman. When the bartender attempts to shoot him, Johnny returns fire and a gunfight ensues, during which Laren escapes and rides off with Johnny in pursuit. Johnny catches him and arrests him. Later, as Johnny leaves, Judy, Joe and Dusty thank him and Dusty announces that he intends to return to law enforcement and run in the next election for the sheriff's job.