Near Border Flats, Don Coyote and his friend Sancho are interrupted on their way to the fiesta by a fight. A quick intervention on their part prompts ranch owner Maggie Riley to hire them. Coyote and Sancho meet her surly, younger brother Ted who is wanting Maggie to sell their cattle herd to pay off a bank loan before they lose the ranch. But when they try to drive a herd to market, a gang led by Big Foot Ferguson drives off their cowhands. Ted finds a surveying plumb marked "United Pacific R.R." in a canyon by their ranch. He shows Sheriff Dave Sherman and they learn that the railroad intends to buy a section of Maggie's land, thereby increasing its value. The next day, Coyote, Ted, the sheriff and three deputies drive Maggie's cattle toward Border Flats, and are waylaid by the Fenton gang. But where is Sancho who has disappeared on a mysterious mission?