A gang of thieves led by the outlaw Gorman are seizing gold shipments from the Davis mine, and local lawmen have been unsuccessful in trailing them to their desert hideout. After mine employee Dick Stonewall is killed with a silver bullet while attempting to deliver a gold shipment into town, special agent Kirk Baxter is summoned to solve the case. Kirk is engaged to Stonewall's sister Beth, and when he learns that her stepfather Carson, the superintendent of the Davis mine, has been abusive to her, he sends her on the stage to stay with his aunt. Unknown to all, Carson is in cahoots with the Gorman gang, sending them messages via carrier pigeon, and although a shipment of gold has been secretly placed on the stage on which Beth is traveling, Gorman robs it after being tipped off by Carson and takes Beth prisoner. Although mine owner Davis refuses to believe that his superintendent has betrayed his trust, Kirk is suspicious of Carson and follows him into town, where he spots Wellford, one of the outlaws. Kirk overpowers Wellford in a fistfight, ties him up and follows his horse to the Gorman gang's hideout. Posing as a friend of Wellford's, Kirk discovers that Gorman runs a silver mine where prisoners, mostly wanderers found in the desert, are forced into slavery and worked to death in the mines. After finding Wellford tied up, Carson sends Gorman a message identifying Kirk as an agent of the law, and Kirk is subsequently taken prisoner. The gang, tipped off by Carson to the delivery of another gold shipment, leaves the mining camp. Back in town, a wary Davis has grown suspicious and insists that Carson accompany him and drive the wagon carrying the gold. After stopping a mine explosion set by one of Gorman's slaves, Kirk frees all of the men and rescues Beth, sending her into town to get the sheriff. Kirk intercepts the wagon before the arrival of Gorman and his gang and has Davis unload the gold, after which he hides in the wagon while forcing a terrified Carson to drive straight into the outlaws' ambush. Once the bandits have climbed aboard the wagon, Kirk spurs the horses and throws the men overboard one by one to be picked up by the sheriff's posse. Gorman makes one last effort to escape on horseback, but is run down by Kirk, who hands him over to the sheriff. A grateful Davis tells Kirk that upon his return from his honeymoon, he will be named the new superintendent of the Davis mine.
