Buck and Manolito lead a group of hands to town to buy supplies. Buck needs 44 ammo but two mountain men bought out the store's supply. Buck telling them he is short of ammo tries to buy some from the men but they refuse. The next day Buck leads the men with the pack mules and supplies back to the ranch. The mountain men were buying supplies for El Lobo who has escaped Yuma prison and his gang of men. El Lobo was jailed when Manolito had him arrested. The men try to convince El Lobo they should steal the pack train but he resists the idea until he hears Manolito is with the group and Pilar, his woman, wants new clothes. He poisons the waterhole the train is going to forcing the pack train to change routes and be short of water. El Lobo traps the group in a box canyon planning to let the heat and thirst do the rest. The men short on ammo and water are hurting when Buck has an idea. They are able to get the dynamite on a pack mule. He rigs a bow and arrow using the strings from Blue's ...