Phyllis Coates, TV's erstwhile Lois Lane, essays one of her largest film roles in Blood Arrow. Coates is cast as a devout Mormon girl whose mission is to transport smallpox vaccine to her friends and neighbors. Unfortunately, this requires her to journey through hostile Indian territory. Appointing themselves as the girl's unofficial protectors are Indian scout Scott Brady, trapper Don Haggerty and (reluctantly) gambler Paul Richards.