The series follows the adventures of Heidi, a young and spirited girl who lives with her gruff but lovable grandfather, Alp-Öhi, in the Swiss Alps. After her father's death, Heidi is sent to live with her grumpy aunt, Dete, in the city. However, Heidi soon finds herself back in the mountains, where she befriends a kind old man, Sebastian, and his granddaughter, Clara. Together, they face various challenges and learn valuable lessons about the importance of family, friendship, and community.