Thirteen-year-old Jonas Ettenberger's parents were killed in a traffic accident. Now the Hamburg city boy has to live with his grandfather in the deepest Bavarian province by order of the youth welfare office. The boy finds it difficult to get used to country life and the Bavarian dialect, as does his widowed grandfather to his grandson, whom he has only just met. But Jonas quickly makes friends with his new classmate Julia Stelzer. In the meantime, Harald Messner, Jonas' uncle, finds out that his nephew has inherited a lot of money. Although he also lives in affluence in Munich, he and especially his new wife Sonja hope to get even more money through Jonas. They appeal to the youth welfare office for custody of the boy and are proved right. Jonas has to return to Munich, even though he is now very happy with Grandpa Ludwig and his housekeeper Rosi.