Act I
Wood nymphs merrily dance and sing along by the lake. Rusalka sits forlornly on the shore. When Rusalka’s father, the Water Sprite, asks what the matter is, she replies that she has fallen in love with a human, who comes often to the lake. Now she wants to become human herself and live on land to be with him. The Water Sprite warns her that humans are evil and full of sin. Rusalka insists, claiming they are full of love and have an eternal soul. The Water Sprite says she will have to get help from the witch Ježibaba. Rusalka calls on the moon to tell the Prince of her love. Ježibaba agrees to turn Rusalka into a human – but warns her that if she doesn’t find love she will be damned and the man she loves will die. Also, by becoming mortal, she will lose her power of speech. Convinced that her feelings for the Prince can overcome all spells, Rusalka agrees. The transformation is complete.
The Prince appears with a hunting party and sees the beautiful maiden by the lake. Even though she won’t speak to him, he is captivated by her beauty and leads her away to his castle.
Act II
The palace servants gossip about the approaching wedding of the Prince and his strange new ride, whose name nobody knows. However, they refer to the old Háta living in the castle, who believes that this wedding will never take place. The Prince wonders why Rusalka is so cold toward him but remains determined to win her. A young lady, invited to the wedding by the old Háta, mocks Rusalka’s silence and reproaches the Prince for ignoring his guests.
Guests are gathering for the wedding and getting ready to celebrate. Rusalka is restless, convinced that the Prince no longer loves her. Rusalka’s father secretly appears in the castle and she begs him for help. The Prince is more and more fascinated by his guest and, irritated by the bride’s meek embraces, pushes her away. Rusalka’s father curses her treacherous groom. The Prince’s guest is frightened, she leaves the Prince and tells him to follow his bride into hell.
Act III
Betrayed and cursed Rusalka has returned to the lakeside forest and grieves for her fate. Ježibaba says that there is only one way Rusalka can be saved: she must kill the Prince. Rusalka refuses. She will not take away the life of her only love.
Her sisters reproach Rusalka for betraying and reject her as well.
The servants, who have been sent to the forest by old Háta, say that the Prince has been bewitched by a strange girl he was going to marry. They ask Ježibaba to save him. Enraged, the Water Sprite banishes them away, saying that it was the Prince who truly betrayed Rusalka.
The wood nymphs enter, singing and dancing, flirting with the Water Sprite, but when he explains to them what has happened to Rusalka, they fall silent and disappear.
The Prince, desperate and half crazy with remorse, emerges from the forest, looking for Rusalka and calling out for her to return to him. She appears from the water, reproaching him for his infidelity, and explains that now a kiss from her would kill him. Accepting his destiny, he asks her to kiss him to give him peace. She does, and he dies in her arms. Rusalka prays for his soul and disappears into the water.
Act 1
A meadow by the edge of a lake
Three wood-sprites tease the Water-Gnome, ruler of the lake. Rusalka, the Water-Nymph, tells her father she has fallen in love with a human Prince who comes to hunt around the lake, and she wants to become human to embrace him. He tells her it is a bad idea, but nonetheless steers her to a witch, Ježibaba, for assistance. Rusalka sings her "Song to the Moon", asking it to tell the Prince of her love. Ježibaba tells Rusalka that, if she becomes human, she will lose the power of speech and immortality; moreover, if she does not find love with the Prince, he will die and she will be eternally damned. Rusalka agrees to the terms and drinks a potion. The Prince, hunting a white doe, finds Rusalka, embraces her, and leads her away, as her father and sisters lament.
Act 2
The garden of the Prince's castle
A Gamekeeper and his nephew, the Kitchen-Boy, note that the Prince is to be married to a mute and nameless bride. They suspect witchcraft and doubt it will last, as the Prince is already lavishing attentions on a Foreign Princess who is a wedding guest. The Foreign Princess, jealous, curses the couple. The prince rejects Rusalka. Rusalka then goes back to the lake with her father the Water Gnome. Though she has now won the Prince's affections, the Foreign Princess is disgusted by the Prince's fickleness and betrayal and she scorns him, telling him to follow his rejected bride to Hell.
Act 3
A meadow by the edge of a lake
Rusalka asks Ježibaba for a solution to her woes and is told she can save herself if she kills the Prince with the dagger she is given. Rusalka rejects this, throwing the dagger into the lake. Rusalka becomes a bludička, a spirit of death living in the depths of the lake, emerging only to lure humans to their deaths. The Gamekeeper and the Kitchen Boy consult Ježibaba about the Prince, who, they say, has been betrayed by Rusalka. The Water-Goblin says that it was actually the Prince that betrayed Rusalka. The wood-sprites mourn Rusalka's plight. The Prince, searching for his white doe, comes to the lake, senses Rusalka, and calls for her. He asks her to kiss him, even knowing her kiss means death and damnation. They kiss and he dies; and the Water-Goblin comments that "All sacrifices are futile." Rusalka thanks the Prince for letting her experience human love, commends his soul to God, and returns to her place in the depths of the lake as a demon of death.