Two men ambush Buck and take his horse, Silver-B, to an outlaw gang's hideout called "Devil's Island", a fortress surrounded by a deep gorge and accessible only by a rock bridge. The outlaws track Buck to a sheriff's office, where they try to kill him but fail and one of the outlaws is captured. Buck disguises himself as the captured outlaw and plans to take a wagon-load of dynamite to blow up the doors to the fortress.; Buck helps Ed Norris, the new sheriff of Pleasant Valley, improve the speed of his draw and gain self-confidence.; Possibly factual story of an incident involving Sioux Indians, telegraph lines, and lightning.; Facts about the uses of the cowboy's bandana.