Mexican General Calleja (Armendariz) runs Zona Libre, a small enclave at the U.S.-Mexico border. For those running from the law--or the lawless--Zona Libre offers sanctuary, for a price. New arrival Confederate officer Clete Mattson (McCrea) shows up with a cool $2 million in gold, looking to buy guns for the Confederacy. Hot tamale Carmelita (De Carlo) fancies Mattson, but the General has dibs on her, and can Mattson trust these guys at Zona Libre, anyway? Either way, trouble's a brewin'.