"Heidis Lehr- und Wanderjahre" by Johanna Spyri is a children's novel published in 1880. Five-year-old Heidi is sent to live with her reclusive grandfather high in the Swiss Alps, where she discovers freedom and friendship among the mountain folk. Her peaceful existence is disrupted when she's taken to Frankfurt to become companion to a wealthy invalid girl. Torn between two worlds, Heidi must navigate city constraints while longing for her beloved mountains and the life she left behind.