Border Patrol agent Lt. Fletch Roberts (Bruce Edwards) is lured into an ambush and murdered, the killers stealing a herd of horses and fleeing across the state line, where the Border Patrol agents can't follow. After Roberts' brother Tim (William Henry) is implicated in the murder, his best friend Lt. Rocky Lane (Allan Lane) goes undercover across the state line to find out the truth about the murder. Rocky poses as an outlaw to infiltrate the gang and find out more information. With help from Tim, local pharmacist Nugget (Eddy Waller), and his horse Black Jack, Rocky is able to track down the real killer and save the herd of stolen horses.
