In Revolution-torn 1913 Mexico, Juan Miranda, a Mexican outlaw leading a bandit family, robs a coach of wealthy men and rapes a female passenger who insulted him. Passing by on a motorcycle is Sean H. Mallory, an early Irish Republican explosives expert, who is working in Mexico as a silver prospector. Juan, who mistakenly thinks Sean's name is 'John' and keeps calling him John thereafter discovering his skill with dynamite and nitroglycerin, asks 'John' to help him rob the Mesa Verde National Bank. After John initially refuses, Juan frames him for the murder of his employer and several soldiers, making him a wanted criminal and offering to "protect" him in exchange for his help. John reluctantly agrees to help Juan rob the bank, but escapes on the way to Mesa Verde.