It is Prince Siegfried's birthday and his mother presents him with a bow, as a gift. She is anxious that he should seek a wife and marry, but he refuses. He sees a flock of swans and decides to go hunting, alone.
On arrival in the forest, he is surprised to find out that the swan at whiche he was aiming is in fact, a woman, transformed into a swan-like form by the evil Baron Rothbart. She explains to Siegfried that she is the Queen of the Swans, Odette, and can only fully cecome a woman again when a man swears undying love for her to break the spell.
The angered Rothbart tricks Siegfried by taking his daughter, Odile, to the Prince's betrothal party, where he must choose a wife. Odile looks very similar to Odette and Siegfried swears his love for her, only to realize that he has been cruelly tricked, as the betrayed Odette appears.
Siegried follows Odette to the forest and pleads her forgiveness. Together, their love is strong enought to endure Rothbart's curse. Rothbart, now powerless, dies. Odette and Siegfried are united forever.