The tainted sheriff in this narrative is Henry Plummer, who arrived in Nevada City, a gold camp in California's high Sierra, in 1852 and soon had two murders to his credit-both the results of bawdy-house brawls. Ten years later he was a full-fledged villain directing a gang of criminals. In 1863 Plummer moved into the Territory of Idaho, which included present-day Montana, and was elected sheriff despite his doubtful past. But it was there that...