Heidi, a five-year-old orphan entrusted to her aunt Dete after her parents' deaths, is taken to the Swiss Alps when Dete seeks work in Frankfurt. There, she joins her reclusive paternal grandfather, Alm-Onji, feared by villagers due to rumors about his past. Living in isolation with his dog Josef, Alm-Onji initially avoids the village, leaving Heidi without schooling and illiterate. Yet Heidi's natural enthusiasm, curiosity, and intelligence quickly forge a bond between them. Her days revolve around the mountain with Peter, the eleven-year-old goatherd tending the village flock. She visits Peter's blind grandmother regularly in winter, deeply moved by the woman's inability to see the natural world. Heidi develops a profound connection to the Alpine landscape and its animals, forming a special attachment to a goat named Yuki (Snowflake). Life on the mountain is simple and deeply satisfying. This period ends abruptly when Dete returns, intending to take Heidi to Frankfurt as a companion for Clara Sesemann, the wheelchair-bound daughter of a wealthy man. Dete deceives Heidi with a promise of a short trip to buy gifts, then leaves her under the stern governess Miss Rottenmeier's care. In Frankfurt, Heidi befriends Clara, whose sheltered existence is brightened by Heidi's Alpine tales. Heidi's unfamiliarity with urban life causes unintentional disruptions, culminating in her smuggling a kitten into the mansion, which Miss Rottenmeier confiscates. Heidi struggles under a consuming longing for the mountains, worsened after Clara's grandmother, who had taught her to read, departs Frankfurt. Forbidden from speaking of the Alps, Heidi declines emotionally and physically, manifesting nocturnal wandering that alarms the household. A doctor diagnoses severe homesickness, advising her return. Mr. Sesemann arranges her journey back, promising Clara a future visit. Reunited with her grandfather, Heidi's joy and newfound literacy inspire him to restore a village house for winter, enabling her to attend school. This move integrates them into the community, softening Alm-Onji's relationship with the villagers. Heidi's influence encourages Peter to discover carpentry skills; he builds a sled and wins a local race. Later, Clara visits the Alps with the disapproving Miss Rottenmeier. Clara's grandmother dismisses the governess upon observing Clara's physical improvement. Encouraged by Heidi, Peter, and Alm-Onji, Clara undertakes physical therapy in the mountain air. She eventually walks unaided, departing with a promise to return. Heidi remains on her sun-drenched slopes, embodying resilience and a deep connection to nature.