Heidi, a little orphan, is taken to stay with her grandfather. Then she has to leave him and move to Berlin to live with her aunt Dete, whose difficult daughter Clara needs a companion. Clara does not like her new little sister at all. Heidi has but one goal in mind: to get back to her grandfather. But her attempt to escape fails. After that Clara at least starts to show her some respect. Heidi supports Clara and convinces Dete to take her daughter to a concert of her favourite band. Dete forgets all about the concert. The same evening Heidi takes the train to Switzerland, back to her grandfather. He is overjoyed to have her back with him.