When Dave Underwood orders his son Bill to foresake the family ranch to run the Underwood stagecoach line, Bill refuses and strikes out on his own, accompanied by ranch hands Smokey Ryan and Whopper Hatch. After returning to his office in town, Dave is visited by Steve Farley, the lawyer who is representing him in a deal to buy the Kellogg stagecoach line in Durango. Farley tells Dave that Kellogg is demanding $40,000 for his franchise. In reality, Farley has offered Kellogg $10,000 for the business, which the crooked attorney plans to purchase for himself. Meanwhile, Bill, Whopper and Smokey are riding the trail to Durango when they see the Kellogg stage attacked. The three ride to the rescue and escort the wounded driver, Hank, back to town, arriving just as Farley's henchman, Slick, incites the other drivers to quit. Farley is pressuring Nancy Kellogg, who is managing the line for her injured father, to sell the business just as Bill walks into the office, introduces himself as Bill Dawson and offers her his services. After Nancy hires Bill, Whopper and Smokey to replace her drivers, Bill invites her to a dance that night. At the dance, Farley tells Slick to frame Bill by planting some stolen mail in his saddlebags, but Bill sees Slick fumbling with his saddle and chases him away. Next, Farley orders his men to pose as passengers and rob the stage, but Bill thwarts his plan by leaving ahead of schedule. When Farley pressures Kellogg to sell his business, Bill convinces him to hold out for a fair price. To prevent Dave from spoiling his deal, Farley visits the old man's office. Farley misses Dave, but sees Bill's photo on his desk and rides back to Durango, where he exposes Bill's identity. After firing Bill, Nancy announces that she will ride shotgun on the afternoon stage. If the Kelloggs fail to deliver the mail, they will lose their government contract, and consequently, Farley instructs Slick and his gang to rob the stage. Bill, Whopper and Smokey follow Farley to his hideout, and recognizing Slick and the others as the outlaws who wounded Hank, the three intercept Nancy's stage and take the mail for safekeeping. They then pursue Slick and his gang as Nancy and Hank return to town. When Dave arrives in Durango, Kellogg informs him that he has sold his business to Farley. Soon after, Bill rides into town with Slick in custody. After Slick confesses Farley's duplicity, Bill goes to the lawyer's office, confronts the crooked attorney and salvages the Kelloggs' stagecoach line. All ends happily as Nancy forgives Bill, and Bill convinces his father to make the Kelloggs his business partners.