At the core of this book is an appalling double murder committed by two Mormon Fundamentalist brothers, Ron and Dan Lafferty, who insist they received a revelation from God commanding them to kill their blameless victims. Beginning with a meticulously researched account of this “divinely inspired” crime, Krakauer constructs a multilayered, bone-chilling narrative of messianic delusion, savage violence, polygamy, and unyielding faith. Along the way, he uncovers a shadowy offshoot of America’s fastest-growing religion, and raises provocative questions about the nature of religious belief. Krakauer takes readers inside isolated communities in the American West, Canada, and Mexico, where some forty-thousand Mormon Fundamentalists believe the mainstream Mormon Church went unforgivably astray when it renounced polygamy.