At the beginning of the 1913 Mexican Revolution, greedy bandit Juan Miranda and idealist John H. Mallory, an Irish Republican Army explosives expert on the lam from the British, fall in with a band of revolutionaries plotting to strike a national bank. When it turns out that the government has been using the bank as a hiding place for illegally detained political prisoners -- who are freed by the blast -- Miranda becomes a revolutionary hero against his will.

Macho Callaghan is a lieutenant in the Federal Guards and his job is to capture Butch Cassidy, Ironhead, and their band of outlaws. Getting in touch with Ironhead, Macho finds a way of being hired by the outlaws. But when the two leaders quarrel and decide to separate, Macho manages to convince Ironhead to attack Butch Cassidy.