Thanks to his prowess with a gun, Dave Robles (Anthony Quinn) makes a place for himself in Mesa, becoming sheriff after out-dueling several gunfighters in a single day. But Robles, a Mexican, seethes over the town's racism, and is warned by kindly nurse Estella (Katy Jurado) that without his gun, he would not last very long. That theory is put to the test when the new sheriff injures his wrist fighting with Ed Bannister (Peter Whitney), who upon learning about it, challenges Robles to a duel.