Ver en Cuevana. For the "Festival of good ideas" that is to take place in their residential quarter the musically enthusiastic young Bum wants to rehearse a music show along with his friends. With pans, cans, hooters and other junk they make music. Some adults get angry about that. Others like the second-hand dealer Dohlenei and Mr. Kling from the symphony orchestra help the children to make their fantastic idea come true.