Near Preston, Arizona, Indians are making repeated raids on wagon trains and stagecoaches. Marshals Hoot and Ken are commissioned to determine why the Indians are breaking their treaty. Hoot gets the idea to enlist the aid of recently convicted killer Duke Dillon to finger the man responsible for inciting the Indians, as Dillon is likely to know the culprit. Hoot and Ken arrange to have Dillon released from custody as soon as he arrives in Preston. When Hoot and Ken learn that the stagecoach on which Dillon is riding with a marshal is likely to be attacked by Indians, they ride ahead and defend the coach from the attack. During the furor, Dillon kills the marshal and escapes, and the stage driver, Betty Conway, pulls the stagecoach safely into Preston with Ken and Hoot as her escorts. Hoot and Ken are arrested for the marshal's murder, but they escape from jail and track Dillon to a remote cabin. Although Dillon double-crossed them, they still enlist his help, and take him to Preston. Dillon immediately goes to the office of the Indian agent, John Hampton, who has been cheating the Indians of their government-alloted cattle with the help of a trusting tribe member, Barking Fox. When Hampton learns that Eagle Eye, a scout, has made arrangements for Chief Thunder Cloud to meet with Hoot and Ken, Hampton plans to sabotage the meeting. Dillon confronts Hampton, who took over his business when he left, and demands to be paid off. Ken follows Dillon into Hampton's office, while Hoot gets the sheriff, but Dillon disappears into a secret passage and Hampton claims not to know of him. While Hoot goes to meet with Thunder Cloud, and Betty meets with her fiancé, the captain of the cavalry, Ken sneaks into Hampton's office and obtains his receipts. Hoot returns and says that Thunder Cloud has received about 30 head of cattle, although Hampton's receipts show that he delivered 600. Barking Fox overhears their conversation and angrily accuses Hampton of stealing from his people, but Hampton has him taken away. Hampton decides to make an escape while he still can, but when he takes the money from his safe, Dillon shoots him and escapes through the secret passageway. Ken and Hoot chase Dillon into the hills, and are followed by Hampton's gang, who are led by Dillon's cohort Spike. Hoot shoots Spike and Dillon, both of whom have tried to kill Ken, and Spike falls from the cliff where he was fighting with Ken. The cavalry arrives as arranged by Betty, and shortly after, the Indian tribe arrives to help in the gunfight. Dillon dies and the thieving gang is rounded up.