During the 1912 Mexican Revolution, rebel leader Hector Cordoba (Raf Vallone) and his bloodthirsty revolutionaries slip across the Texas border and liberate a number of cannons from a U.S. Army fort. Under direct orders from General Pershing (John Russell), Captain Rod Douglas (George Peppard) heads into Mexican territory to face down Cordoba and get back the American cannons with the help of Mexican military officer Antonio (Gabriele Tinti) and alluring local Leonora (Giovanna Ralli).