A Lost Lady is the story of the Forresters, Marian and Daniel, who live in the West along the transcontinental railroad. The story is told from the perspective of Niel Herbert, a young local who idolizes Mrs. Forrester. Over the course of the narrative, Marian declines both mentally and physically as the frontier culture of her town fades with the onset of American law. Eventually her husband dies and her life falls into disarray.