Captain Curtis, who is investigating certain shady traffickers of goods at Fort Defiance, is killed by the vile Captain Rossiter’s hired ruffians, who attack the stagecoach on which the officer was traveling, escorting young Jos, the son of Colonel Barry, commander of the outpost. Some young Navajos who witnessed the aggression, help the child, taking him to their camp, but the blame for the infamous murder falls on them and they are unjustly arrested by Barry himself. Tex and Carson thus start looking for those really responsible for the crime.