James MacLaren, once a resourceful and ambitious Hudson’s Bay Company trader, has renounced his aspirations for a quiet family life in the Bitterroot wilderness. Yet his life is overturned in the winter of 1846, when his Nez Perce wife deserts him and his children die of smallpox. In the grip of a profound sorrow, MacLaren, whose home once spanned a continent, sets out to find his wife. But an act of secret vengeance changes his course, introducing him to a different wife and mother: Lucy Mitchell, journeying westward with her family.