"If America was a melting pot, Butte would be its boiling point," observes Morrie Morgan, the itinerant teacher, walking encyclopedia, and inveterate charmer last seen leaving a one-room schoolhouse in Marias Coulee, the stage he stole in The Whistling Season. A decade later Morrie is back in Montana, as the beguiling narrator of Work Song. Lured like so many others by "the richest hill on eart...