Wild Horse Range (1940)

Horse traders Jack Wallace and his partner Manny discover they are being undersold by a dealer named Arnold, and Jack is certain Arnold is selling stolen stock. He traces the Arnold horses to a ranch owned by Ann Morgan and her Aunt Harriet, and finds that crooked-foreman Stoner and most of the hands blame the horse stealing on a white stallion (Starlight the Wonder horse in stock footage) who lures the mares away. Jack and Manny uncover the hideaway of the cached-Morgan ranch horses, and free them before Arnold can run them across the (always-handy) border. The stallion aids them by leading the horses out of the clutch of the outlaws. A terrific fight between the outlaws and Jack and Manny ends with the sheriff taking the outlaws prisoners, the mares returned to their rightful owners, and Jack and Manny established at the ranch.