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.

Wendel's suspicions are confirmed. For as long as he can remember he has believed that he was switched at birth. In the shock of retirement, he decides to finally get to the bottom of the matter. A lock of hair from his deceased mother allows only one conclusion in the DNA test. Wendel is not Wendel. But then who is he? In search of his presumably aristocratic origins, he meets a countess who is as resolute as she is fascinating.