Slim Sherman and Jess Harper are in Jackson City to buy cattle from George Lake. Arriving in Jackson City late at night they enter the saloon where Jess runs in an old friend named Mason who has changed his name to George Lake. When he reneges on the deal, it leaves Slim steaming mad and ready for a fight. After a scuffle Slim leaves the saloon to go to the hotel but when a shot is heard, he is found standing over the body of George Lake. The sheriff refuses to investigate as circumstantial evidence points to Slim as the murderer. Jess is Slim's only hope to clear him of the murder. The puzzle gets only more convoluted with a odd assortment of characters all looking for a Durango cavalry spur that is purported to contain a map to the fabled Lost Dutchman Mine. Lake was murdered for it and the only man that can clear Slim wants it. With everyone double-crossing everyone else, Jess has to find the spur if he wants to save Slim. He just has to live long enough to do it.