Lon Walker is an outlaw with a price on his head, but the manager, Raymond Harper, of the Black Hills Division of Wells Fargo is sure Lon is the only man tough enough to stop the holdups that are ruining the company's business. Against the protests of Marshal Harvey Dorman and banker James Phelps, Lon is given the job. Dorman sourly agrees to give Lon thirty days immunity from arrest to complete the task. He refuses at first but when he and Deputy Sheriff Deadeye learn that Mr. Southern, father of recent-arrival Gail, has been murdered in a stagecoach robbery, he accepts. Local gunfighter Vic Fowler vows to get him if he carries on, and he has to shoot another gunmen, Bart Cassidy, when baited into a fight in the saloon. Through Gail, who works in the bank, Lon learns that someone using the name "Namrod" has been making large deposits in the bank on dates and amounts that correspond to the stage robberies. He notices that the spelling of "Namrod" backwards is Dorman, but he still has no actual proof that the Marshal is on the receiving end of the robberies.