Larry Munro has discovered a vein of platinum on his ranch. A group known as the Secret Seven has learned about it and plan to get the Munro Ranch. Kentucky Wade and his friends arrive to help Larry and are soon fighting off attempts on their lives by the henchman of the Secret Seven and the Indians they enlist by bribing them with rifles.
A short plot summary finds Wild Bill Hickok (Bill Elliott), the U.S. Marshal in Abilene, Kansas, opposing the Phantom Raiders, a gang of renegades raiding the cattle drives over the Chisholm Trail from Texas to Abilene. Hickok organizes the boys of the town into the "Flaming Arrows" to assist him. Finally, in the 15th chapter, "Trail's End", Hickok, the "Flaming Arrows" and army scout Kit Lawson (Kermit Maynard) combine to put an end to the Phantom Raiders.
Buck Sherman and Jake Jackson, a couple of evil carpetbaggers, illegally enter a Navajo reservation to prospect for gold and end up killing Aranho, the Navajos chief. Black Arrow, presumed Aranho's son, refuses to kill the Indian agent, Tom Whitney, in revenge, as demanded by Navajo law. Then, he is driven off the reservation for his reluctance to kill Whitney and decides to join forces with Pancho, Mary Brent and the agent to go in search of the men who killed the chief.
Rex, a wild stallion, and Rinty, a police dog, are pals. Their master , John Sheldon, is framed for murder, and Alice Ingram plans to race Rex for money to pay for John's legal defense. Meantime, Frank Nolan, who has falsely accused John, sets out to steal Rex for himself.