The film is about an young orphan girl named Heidi who is sent by her strict aunt to live with her grandpa in the Swiss Alps, but just as she starts to adjust to living with him, her aunt takes Heidi back to the city where she works as servant girl to a rich, but very strict family and their handcapped daughter, Klara.
When Heidi attempts to help Klara find fun ways to help her feel better, she is locked in a basement by Klara's parents & it's up to Klara & Heidi's countryside friends to help rescue her.
- Lorne Greene as Grandfather
- Margery Gray as Heidi
- Fritz Feld as Sebastian
- Joan Gerber as Rottenmeier
- Pamelyn Ferdin as Klara
- Roger DeWitt as Peter
- Virginia Gregg as Aunt Dete
- Richard Erdman as Herr Sessmann
- Michael Bell as Willie
- Janet Waldo as Tinette
- Peter Cullen as Gruffle
- Frank Welker as Schnoddle & Hootie
- Michael Winslow as the Mountain
- Sammy Davis Jr. as Head Ratte
Heidi's Song debuted at #7 at the box office, grossing $1,416,713 during its opening weekend. Domestically, it made $5,124,391.
Janet Maslin from the New York Times said the movie was "a better film for small children than for older ones" and also said that "it offers just what they're accustomed to on Saturday morning television, only it's longer".