The rulers of the two kingdoms, King William and Queen Ubert, decided that when their children grew up, they would join the two kingdoms by marriage.  Derek and Odetta do not fall behind each other, but they fall in love with each other during the last meeting. Odette, disappointed by the confession that Derek only likes her beauty, returns with her father to the kingdom. Along the way, they meet William's former enemy, the sorcerer Rothbart, who killed the king and kidnapped Odetta, and then cursed her - during the day he is a swan, and every evening when the moonlight falls on the lake, he becomes a human. Odetta lives in an enchanted lake , where she befriends the frog Jean-Bob, the fast turtle and the puffin bird . Derek decides to defeat Rothbart  and go to the rescue of Odetta , who can be saved by a promise of undying love .