A young tenderfoot goes to Death Valley to work at his fiancée's borax mine. He is assigned to work as a swamper on the huge mule train that ships the product out of the desert to a train station ten days away. On the return trip, a disgruntled former employee steals the mine's payroll and shoots the lead driver, forcing the tenderfoot to prove his mettle by taking the train back to safety and tracking down the thief to retrieve the stolen money.