Jacob Gamble and his crazy brother Ishmael are sworn enemies. But when they finally meet up at an old mission church in the desert to settle their feud, they find a score of massacred bodies ... and one mortally wounded survivor who promises them riches beyond their wildest dreams if they return his prized possession to Canyon Diablo. Problem is, Canyon Diablo is the deadliest town on the frontier. A cutthroat named Boss Rex runs the place with murderous zeal and he's been waiting for a chance to settle an old score with Jacob. The brothers will have to call a truce - and use all of their shooting skills - if they aim to collect the treasure and get out of Canyon Diablo alive.