At the great tournament, the small Knight Rost causes a sensation when he wins a duel against the previously undefeated Prince Protz. The humiliated Protz accuses Rost of being a thief and a fraud, and tricks the King into revoking Rost's knight licence and boarding up his castle. Even worse, the fair maiden Bö turns her back on Rost. Nevertheless, Rost won't give up. Accompanied by his horse Feuerstuhl and Koks, a benevolent dragon, he sets out to restore his honor and to win back the love of his life.