Open Midnight weaves two parallel stories about the great wilderness — Brooke Williams’s year alone with his dog, ground truthing backcountry maps of southern Utah, and that of his great-great-great-grandfather, William Williams, who in 1863 made his way with a group of Mormons from England across the ocean and the American wild almost to Utah, dying a week short. The story follows two levels of history — personal, as represented by his forbear,...