Dick Lazarus and his raiders are feared on both sides of the Rio Grande. Landowners and townspeople alike have been victim of his vicious attacks, and Lazarus's operation of blackmail and threats means no one is willing to assist the lawmakers in their efforts to capture him. Lazarus's increasingly daring crimes see him raid the ranchero of the Robles family in Mexico. This time he escapes not only with a herd of horses, but a hostage - Luis Robles - who should fetch a hefty ransom. Dan Calloway, the owner of the stolen herd and Luis' friend, is determined to rescue Luis and regain his possessions. Ignoring the warnings, and with an unexpected ally on his side, he pursues Lazarus across the Rio Grande, along the Tonto Rim and then back to Mexico.