Indians and Mexicans harass the military. An exceptional truce between Northists and Southerners is declared in order to discover who these outlaws are that exhaust the forces of each camp. Küstler takes advantage of the insubordination of Chesterfield and Blutch to degrade them and entrust them with a mission of infiltration into the rebels. They will be hired as cowboys at a ranch led by Mac Coy, an unscrupulous vaurian in the service of the Mexicans whose irascible chief Gonzales sells meat damaged to the Indians...