During the Mexican Revolution, a Durango-bound government munitions train is forced to stop due to the presence of a crucifixion army officer on the tracks. El Chuncho Muños, a gun runner loyal to the revolutionary leader General Elías, leads his gang in an assault on the train. Lieutenant Alvaro Ferreira attempts to save the officer, but upon being fatally wounded by Chuncho, he is forced to order the train to run the officer over and escape the bandits. Bill Tate, an American passenger on the train, kills the train driver and stops the train again, allowing Chuncho and his gang to kill the remaining soldiers and take their weapons. Posing as a former prisoner of the army, Tate joins the gang, and is quickly befriended by Chuncho, who nicknames him "Niño".