The Pony Express days are coming to an end, with riders John Blair (John Wayne) and his friend Larry Adams (Lane Chandler), both about 75 pounds too heavy for the original job description, out of a job. They pay Cal Drake (Douglas Cosgrove) of Buchanan City a big price for the Crescent City line and equipment, and arrive there to find it is a ghost mining town and has only two residents: eccentric, self-proclaimed Mayor "Rocky" O'Brien (Lew Kelly) and Dr. William Forsythe (Sam Flint). With the arrival from back east of Barbara Forsythe (Phyllis Fraser), the doctor's daughter and Ginger Rogers lookalike, O'Brien happily changes the blackboard population sign from two to five. John determines to get even and operate the line anyway, after vacating a resident skunk from the stagecoach. On his first run into Buchanan City John learns of a coach race to be staged (fastest team to win a $25,000 government mail contract) and he signs up. A telegraph crew, drinking unknowingly of a poisoned well, are saved by John's timely arrival on the scene,and agree to run their line through Crescent City if John can get laborers.He takes them from Buchanan City, leaving it nearly deserted and O'Brien wearing out his chalk changing the population sign upwardly in Crescent City.Drake decides to get rid of John by hiring him, for $1,000, to drive a gold shipment to Sacramento, and ambushing him. John evades the ambush by taking another route and returns to collect his thousand dollars at gunpoint. As the race for the mail contract starts, Drake and his henchmen throw many obstacles in John's way.