Hanni and Nanni are not only sisters, but also best friends. The twins are inseparable and always up to something. When they cause a wild chase through a department store, their wealthy parents have had it: They send the girls to the posh boarding school Lindenhof in order to teach them some manners. While sweet-tempered Nanni quickly makes new friends, the impulsive Hanni has a hard time accustoming herself.