In the west of the United States, a patrol of the 22nd Fort Bow Cavalry Regiment manages to rescue a messenger from the hands of the Comanches. This one belongs to the Fort Defiance garrison, one of the main outposts of this area, which is under siege and is short of ammunition. Commander Appletown will therefore designate Sergeant Chesterfield to transport a cart filled with ammunition to Fort Defiance. Blutch, Tripps and Bryan who accompany the sergeant and escort the cart will have much to do in this infested area of Indian people...