Prince Siegfried chances upon a flock of swans while out hunting. When one of the swans turns into a beautiful woman, Odette, he is enraptured. But she is under a spell that holds her captive, allowing her to regain her human form only at night.
The evil spirit Von Rothbart, arbiter of Odette’s curse, disguises his daughter Odile as Odette to trick Siegfried into breaking his vow of love. Fooled, Siegfried declares his love for Odile, and so dooms Odette to suffer under the curse forever.