Josa is too small and too weak to become a charcoal burner - like his father. This makes him very sad. Then his bird friend gives him a magic fiddle and teaches him to play it. With it, Josa can, just as he likes, make his listeners grow and grow smaller. So he sets off for the moon to play to it. On the long way there he experiences a lot of adventures with the help of his magic fiddle. In the end, he finds the moon and makes it grow and become smaller.