While on the trail of a vicious criminal and his female accomplice, lawman Harry Stevens asks his nephew Bob to accompany him on the case. Claiming that he is not yet ready to settle down, Bob declines his uncle's offer to recommend him for the position of U.S. Marshal. After bidding farewell to Bob, Harry continues on his mission alone, tracking the female accomplice, Blanche, to the Tracy Hotel. At the hotel, Harry is about to arrest Blanche when her partner, Slade, sneaks up from behind and kills him. Slade and Blanche, posing as a schoolteacher, then hurriedly board the stage bound for Logan. When robbers attack the stage, Blanche, feigning hysterics, runs into the bushes and disappears, eventually joining the outlaws. After being notified of his uncle's murder, Bob and his friend Hoot, meanwhile, become U.S. Marshals, vowing to bring Harry's killers to justice. Later, in Logan, Blanche, now disguised as a French frontier woman, buys a ranch. Upon discovering that a geologist has been testing for oil in the region, Slade instructs Blanche to extract the specifics from the geologist. Bob and Hoot, meanwhile, trace Blanche to Logan and proceed there. In town, Blanche flirts with the geologist and tricks him into showing her his maps, which reveal a deposit of oil on her land. Soon after, the geologist is found stabbed to death in his room, and consequently, when Bob arrives in town, posing as a drifter, he is suspected of murder. Soon after, Hoot comes to town and introduces himself as land developer Cornelius Parkford. When Bob stages a confrontation with Hoot in the Logan saloon, the sheriff orders Bob to leave town, and Hoot warns that Bob is a dangerous outlaw named Cheyenne. Impressed by Bob's audacity, Jed, one of the outlaws, invites Bob to join the gang. At their camp outside of town, Denver, another outlaw, explains that they have been robbing the stage to amass enough money so that they can drill for oil. Under the pretense of visiting his sweetheart, Bob rides into town that evening and meets Hoot in the dead geologist's hotel room. Having found the map, Bob suggests that it was the motive for murder and states that the next step is to uncover the gang's leader. Suspecting that Blanche is the woman whom they were trailing, Hoot rides to her ranch and introduces himself. Now certain that Blanche is their prey, Hoot proposes that Bob court her, causing her partner to become jealous and reveal himself. The next day, the gang holds up another stage, and when Bob brazenly exposes his face, Denver criticizes him and a fight ensues. Upon reaching town, the stage driver identifies Bob as one of the robbers, and the sheriff rides out after him. Using the sheriff as an excuse, Bob gallops to Blanche's barn and asks her for refuge. After Blanche points the sheriff in the wrong direction, Bob flirts with her and returns to the ranch later that evening. Denver, incensed by Bob's actions, reports the meeting to Slade, who orders him to eliminate Hoot. The next day, Hoot is driving his carriage along the trail when Denver rides up and shoots him. After finding the wounded Hoot lying in the dirt, one of the townsfolk takes him to the doctor for treatment. That night at the camp, Denver attacks Bob, causing Bob to announce that he is leaving the gang. When Jed asks to join him, the two ride off together. Deciding to confront Blanche, Slade rides to her ranch and finds Bob waiting for him. The other members of the gang then arrive, Bob pulls his gun and is about to arrest them when a fight erupts. Jed comes to Bob's defense and together they subdue the outlaws. After arresting Blanche, Bob informs her that the man she killed was his uncle.