The story is about an orphan girl, Heidi, who has been sent to live with a lonely, angry man at the top of a mountain in the Swiss Alps. This man is her grandfather. Heidi had been previously living with her Aunt Dete, but now Dete has been appointed to a job in Frankfurt. There is no way she is going to turn down this job to look after Heidi; she has to go. Surprisingly, Heidi's grandfather turns out to be welcoming and loving and lets Heidi stay in his mountain home, which she adores.