Rusalka the water nymph longs for a human soul and to experience human love. The three wood nymphs entice the Water Goblin Vodník to leave his element. He mourns his lost youth. Rusalka confesses her longing to join the human world to the Water Goblin, her ‘dear father’. His warnings do not deter her.
Rusalka calls upon Ježibaba the witch, and begs her to turn her into a human being. For this transformation to take place, Rusalka must sacrifice her voice. If she does not attain love, she will fall prey to the curse of the water powers. The Prince has lost his way tracking a white doe in the forest. He encounters a mute young woman: Rusalka. The pair fall in love.
The Gamekeeper gets the Kitchen Boy to tell him all about the feast being prepared at the castle. The Kitchen Boy informs him that the Prince is determined to marry the ‘mysterious being’ that he brought from the forest a week previously. The Prince reproaches his bride for her coolness. The Foreign Princess complains that his wedding guests are being ignored. The Prince blames Rusalka and the wedding guests humiliate the bride. Vodník laments the fate of Rusalka, blinded by the glitter of the human world.
The Foreign Princess arouses the Prince’s sensuality. Rusalka watches as the Prince betrays her. Vodník arrives, and threatens the Prince with the words ‘you may hasten into another’s arms, but you will never escape Rusalka’s embrace.’ This threat leads to the Prince’s breakdown.
Rusalka has been cast out by both the human world and the world of nature. Ježibaba recommends that she stab the Prince, claiming that only warm human blood can heal her. Instead, Rusalka chooses to punish herself.
The Gamekeeper and the Kitchen Boy venture into Ježibaba’s territory to consult her regarding the hopeless mental state of the Prince. They blame the ‘faithless enchantress Rusalka’ for his condition. Vodník angrily reminds them that it was the Prince who was faithless, and scares them both off.
Tortured by his conscience, the Prince is searching for his lost love. Rusalka appears to him as an undead avenger. The Prince begs for her deadly kiss. Rusalka kisses him and commends the dying man to the Christian God’s mercy, which she herself is denied.