After cowboys Tucson Smith, Lullaby Joslin and Stony Brooke see outlaw "Fin" Sharkey murder a stagecoach driver, they quickly overwhelm the outlaw. To their surprise, they find an envelope in the stagecoach's mail pouch, which contains a sales receipt in Tucson's name for a thirty-day option on the nearby Tresbarro ranch. With Sharkey in tow, the three men ride to town, where they challenge Brose Glasgow, the corrupt sheriff, and Steve Ogden, the mayor. After forcing Glasgow to put Sharkey in jail, the three cowboys learn that Jeff Ferguson, a former outlaw known as Guadalupe Kid, whom Tucson had recently reformed, had outbid the greedy Ogden for the Tresbarro ranch and then, to prevent Ogden from stopping the deal, had put the option in Tucson's name. Soon after the deal, the ranch's owner was killed, and Jeff, fearing arrest, fled. In Ogden's saloon, Tucson confronts the mayor and demands to see Jeff, who is being held illegally by Glasgow. During the showdown with Ogden and his men, Stony and Lullaby arrive and help Tucson and Jeff overwhelm their foes. The four cowboys then ride to their newly optioned ranch, and Jeff introduces his friends to his sweetheart, Carolyn Sibley, the former owner's ward. Ogden, meanwhile, orders his men to "dry-gulch" Tucson's cowhands and makes a deal with Sundown Saunders to have Tucson murdered. While Tucson is in town investigating the apparent theft of the ranch's deed, he is challenged to an evening showdown by Sundown. Before the gunfight, Jeff tries to convince Sundown to "go straight" and forfeit the fight. Sundown refuses to back down, however, and meets Tucson as planned. Tucson, having deduced that Sundown only fights in the evening because of failing eyesight, fires at him from a distance and wounds him. Then, Tucson takes Sundown to his ranch to recover and asks him to join forces against Ogden. Unwilling to embrace Tucson's ways, Sundown turns him down and prepares to leave just as Glasgow's gang threatens the ranch. During the ensuing hillside shootout, however, Sundown rides up and takes the fatal shot meant for Tucson. After Glasgow's men surrender, Tucson, Lullaby and Stony force a confession out of Glasgow and confront Ogden in his saloon, where he is finally killed. Now the complete, legal owners of the ranch, Tucson, Lullaby and Stony join Carolyn and Jeff as its permanent residents.