The tough poetry of Karen Fisher’s novel buoys this chronicle of Oregon migration along on an incantatory wave. It’s 1847 and dour patriarch Israel Mitchell drags his reluctant wife, Lucy, and their children out to the Oregon Territory. Their paths cross with James MacLaren, a bereaved Scot trapper whose children have all died from smallpox and whose Nez Perce wife has run off. Each day the murderous landscape spools mercilessly ahead of the emigrants, and Fisher’s depiction of a familiar-seeming journey that is not adventurous, as myth would have it, but a daily exercise in folly and survival, is astonishing. A Sudden Country requires a patient reader, but the spell it casts is transformative and rare. The heartbreaking first chapter alone is worth any number of lesser novels.