Heidi's Song (1982)

Orphaned Heidi is sent by her strict aunt to live with her reclusive grandfather in the Swiss Alps countryside. She likes it there and soon brings joy to her grandpa as well as everyone else there, including the animals. She also meets a nice sheepherder boy and befriends him. However, her aunt returns and takes her to the city to live as a servant girl to a cold rich strict family and their nice but sad handicapped daughter Klara. Heidi befriends Klara and finds fun ways to help her feel better, but Klara's strict parents punish Heidi for her actions which they see as childish and irresponsible. She is locked in a basement, where an evil rat lives. At that point, her friends from the countryside, as well as Klara, decide to rescue Heidi and help her go back to her grandpa.