After the death of her parents, the little girl Heidi is raised by her mother's sister, Aunt Dete. After four years, when Heidi was 5 years old, Dete got a good job offer from the noble family Sesemann from Frankfurt. Dete cannot take Heidi to Frankfurt, so she brings Heidi to her Grandfather on the alp.

On the alp at her Grandfather, Heidi is really happy for the first time in her life: she spends every day in the meadows with Peter and the beloved goats and has the opportunity to marvel at the variety of flowers and the beauty of nature.

So two absolutely happy years pass. When Heidi should start school, the pastor appears on the alp. However, the Grandfather thinks the girl will be spoiled in the village and refuses to send Heidi to school. On the same day, Aunt Dete also appears to take Heidi to Frankfurt. There she is supposed to keep company with the disabled daughter of the house - Klara. However, Heidi only goes with her aunt because she promises that she can go back to the Alp immediately if she doesn't like it in Frankfurt.

Heidi expects a completely new and unknown world in Frankfurt: Instead of rustling firs, mountains and meadows, Heidi now meets wide streets, many people and tall houses in the middle of the big city. Klara and Heidi will soon be best friends who play numerous pranks on the evil and tyrannical governess - Miss Rottenmeier. These delight not only the two young girls, but also the servant Sebastian, who quickly proves to be the girls' secret helper. Klara's grandmother quickly took the little mountain girl to her heart and teaches her to read, while Mister Sesemann quickly notices that Heidi is doing his daughter good.

Despite the deep friendship with Klara, Heidi constantly suffers from homesickness, which robs her of sleep. When the doctor catches her when she sleepwalks, he orders her to go home. After two entertaining and amusing years, the farewell is very difficult, especially for Klara. Heidi, on the other hand, enjoys being back on the Alp with her Grandfather, with Peter and their goats and, thanks to the reading courses in Frankfurt, being able to even read Peter's blind grandmother from the book.

Before the next winter, the Grandfather and Heidi moves down to the village and the goats. So Heidi can go to school. Heidi teached Peter and as a result Peter go to school too. After the snow melts in spring, everyone moves to the alp. In a letter from Klara, she wrote that the doctor had prescribed her a cure in Bad Ragaz for the summer so that she could visit Heidi on the alp every day. However, the summer passes without Klara appearing on the alp.

In late autumn only the doctor appears alone. Since the only daughter died a few months ago, his zest for life has vanished. Heidi succeeds in getting the doctor up again and bringing him back the joy of life. Thereupon the doctor leaves Switzerland strengthened and comforted and he tells Klara over and over again how nice it is with Heidi on the alp.

The next summer it will be time. Klara and her grandmother come to visit! However, the jealous Peter, who is afraid that Heidi now has no time for him, has little joy about the visit from Germany. Out of anger he pushes Klara's wheelchair down the mountain, where it crashes.

Thanks to the care of the Grandfather, the fresh mountain air and the goat's milk, Klara is getting stronger and finally learns to walk. When her father also comes to visit the Alp and Klara runs towards him all alone, he cannot believe his own eyes and is overjoyed. When Mister Sesemann asks the Grandfather and Heidi how he can show himself recognizable for the care and recovery of his daughter, the Grandfather only says that he only wishes that Heidi always can be independently and never has to earn her living from strangers.

Heidi's only wish was that Peter's old and blind grandmother be brought the big bed from Frankfurt with a blanket and pillow so that she never had to freeze again. Mister Sesemann promises to fulfill Heidi's wish and assures the Grandfather that he does not have to worry about the future of his grandchild.