In Charleston, South Carolina, at the close of the Civil War, Clay Fletcher, former lawyer and captain in the Confederate Army, eagerly accepts a job to travel West, not wanting to return to his legal career immediately. Clay's mission is to obtain the signature of Henry Jeffers, a criminal prosecutor whom Clay once admired, on some estate papers. On the stagecoach to El Paso, Texas, Clay's wallet is stolen by "Stagecoach" Nellie, and when he then goes into an El Paso saloon, he stumbles into an impromptu trial called by Sheriff La Farge and land developer Bert Donner. Although the defendant insists he shot a deputy in self-defense, the drunken judge summarily convicts the man. Outraged by the injustice, Clay demands a fair trial, and is found in contempt of court by the judge, who Clay discovers is Jeffers. When Clay is unable to pay the fine, Donner starts to auction off his clothing until Clay stops him with his fists. Clay is finally rescued by a Mexican rancher named Nacho Vasquez, who wins back Clay's clothing in a shooting contest with Donner. Later, Clay makes contact with Jeffers' daughter Susan, with whom he had been in love before the war. Susan now runs a ladies' hat shop in El Paso, and refuses to return to Charleston because of her father's alcoholism. Clay intends to return to Charleston immediately after getting Jeffers' signature, but when he sees his army buddy, John Elkins, being beaten by La Farge because he is behind on his taxes, Clay defends John, insisting that veterans have a grace period on their taxes. When La Farge and his gang attempt to arrest John and take his land, John shoots a deputy while defending his family, and Clay helps him escape across the border to Nacho's ranch. Clay decides to stay on in El Paso and represent John at his trial. Clay then arranges with an old trader named Pesky, whom he befriended on his journey, to take Jeffers out of town and keep him sober until the trial. La Farge attempts to murder Clay, but Clay escapes and takes refuge at Nacho's ranch, where he becomes a quick draw with his guns. A sober Jeffers exonerates John at the trial, after which Susan accepts Clay's marriage proposal. The victory celebration that night is disrupted when La Farge's gang drags Jeffers through the streets, killing him, then murders John and his wife, leaving their son Jack an orphan. Clay takes the law into his own hands and forms a vigilante group with ranchers who have been forced off their land by La Farge and Donner. After killing the men responsible for the Elkinses' deaths, the vigilantes wage a campaign of terror against anyone they believe is connected with Donner and La Farge. Distraught by the change in Clay's personality, Susan sends for his grandfather, Judge Fletcher, and they both persuade Clay that he has become as dangerous as the men he pursues. After he kills an innocent minister, Clay agrees to end the violence, but is forestalled when La Farge murders Judge Fletcher. Clay's gang then rides into El Paso in the midst of a dust storm and wages a gunfight in which Donner is killed and Jack is wounded. Clay then prevents the vigilantes from hanging La Farge by convincing them that they must end their own mob rule, and thereafter protect the rights of all people in courts of law. La Farge and his gang are arrested, and with Susan at his side, Clay returns to El Paso to launch a new era of law and order.