This is a Western series set in Mexico during the revolution in the 1910s. We follow two American soldiers of fortune: Pete is an explosives expert and Chett is a pilot ace. The actions take place in semi-historic dramas where they meet several real persons such as revolutionaries Pancho Villa and Emiliano Zapata.
In two stories our heroes even join forces with the fictional hero Blueberry, who was created by Charlier as the main character in his epos set during the American Civil War. By now Blueberry is in his 70s!