After plotting a way to get kicked out of boarding school, the twins diverge for the first time in their lives when Nanni starts enjoying her stay.

Cookie manufacturer Bertram Dinkler with his old-fashioned know-it-all attitude triggers an unexpected fighting spirit not in the teenagers, but in single mother Stefanie Eckhoff. Stefanie challenges Bertram. She wants him to do a sports badge and try to do better than her. Right from the first training session, the rivals realize that they may have gone a little too far. Fortunately, their stubbornness helps both of them to unleash unexpected energy.