Act I: Scene I: THE GARDEN
In a castle garden in medieval Austria, Prince Siegfried gathers with young courtiers to dance and celebrate on the eve of his coming-of-age, a time when he must marry and inherit the kingdom. The royal chamberlain, Lord Wolfgang, entreats the prince to more serious concerns; but the prince continues to revel. The prince's mother, the Queen, enters in a royal procession and presents Prince Siegfried with a crossbow to commemorate the day. The Queen tells the prince that he must choose a bride from among the foreign princesses attending his grand birthday ball the following evening. She responds to his attempt at humor with firm demand and departs. To distract the prince, three of his friends in the court dance a pas de trois. As night falls, the revelers dance in celebration of the prince's eminent betrothal before departing the garden. Alone with his thoughts, the prince is overcome by melancholy; he yearns to find true love and agonizes over the weight of his royal responsibility. A flight of swans passes overhead; Siegfried is intrigued and, with his crossbow in hand, he follows them into the forest well beyond the castle grounds.
Act I: Scene II: A GLADE BY THE LAKE
Deep within the forest, Siegfried watches by the light of the moon as the swans glide on a lake. As he raises his crossbow to take aim, the swans are suddenly transformed into beautiful maidens. Odette, Queen of the Swans, enters the glade and is shocked to see a human there. She tries to fly back to the lake, but realizes she cannot—her wings have transformed into arms. As they stare into each other's eyes, Siegfried and Odette's fated love is determined. Odette tells Siegfried of her tragic circumstance: the sorcerer von Rothbart has cast a spell on her and the other maidens who are turned into swans each day and into human form each night. Only the commitment of true love, pure and unfaltering, can break the spell, yet von Rothbart cannot be destroyed or their plight as swans will be sealed forever. Sensing the approach of von Rothbart, Odette flees and the other swan-maidens emerge from the lake. The lords enter and prepare to defend the prince from these strange creatures. Siegfried tells them to lower their weapons and commands them to return to the castle and to keep secret what they have seen. Odette expresses her gratitude to Siegfried for protecting her swans, and together they dance for him. Siegfried confesses his passion for Odette and begs her to attend the ball so that he may introduce her as his betrothed. Before she can reply, dawn breaks and Odette and her companions are once again transformed into swans. Prince Siegfried returns to the castle, praying to reunite with Odette at the ball. Von Rothbart, who has witnessed the scene, plots to destroy the prince.
Act II: Scene I: THE BALLROOM
At the ball, the Queen summons the visiting princesses from foreign lands who dance for the prince in hopes of being chosen as his bride. The Queen tells Siegfried to make his choice. Siegfried is conflicted by thoughts of Odette, when trumpets announce the arrival of more guests. Well disguised as a wealthy dark knight, von Rothbart enters with his evil daughter, Odile, who is dressed as a black swan princess strangely resembling Odette. With a convincing glance, Odile tempts Siegfried into believing that she is in fact the beautiful swan queen he came to love the evening before and she leads him from the ballroom. National dancers representing the homelands of the princesses-in-waiting perform folk dances for the Queen. Siegfried and Odile re-enter to dance a beguiling pas de deux. Siegfried tells his mother he wishes to marry Odile and presents flowers to Odile as a sign of his intention. Von Rothbart, still in disguise, demands that the prince vow his fidelity. As Siegfried swears his love to Odile, the distressed image of the betrayed Odette appears in the ballroom window and the evil deception is revealed. Von Rothbart and Odile depart triumphant while Siegfried, horrified by his folly, leaves to seek out Odette.
Act II: Scene II: CLIFFS AT THE LAKE
Siegfried finds Odette and begs her forgiveness, which she offers him with a warning that von Rothbart will return to vanquish them. Odette pleads with Siegfried to save himself, but he vows to defend her, even unto death. Von Rothbart interrupts the lovers and quickly overpowers Siegfried with his sorcery. Odette steps between them in an act of selflessness and jumps into the lake. The forlorn Siegfried follows her in an act of redemption. Von Rothbart is destroyed by the lovers' fatal commitment. Dawn breaks and the impossible love of the Prince and the Swan Queen is immortalized in the memory of the lake.