Wotan has been prey to anxiety ever since he stole the ring from Alberich and used it to pay the giants rather then returning it to the Rhinedaughters. Desperate to protect himself should Alberich regain the ring, he has sought out Erda, who bore him the warrior-maiden Brünhilde. Brünhilde and her eight sisters are raising an army of slain heroes to defend Walhalla. Wotan, in the meantime, has also fathered Siegmund and Sieglinde, the Wälsung twins, with a mortal woman. With Siegfried, Wotan hopes to create a free being who will recover the ring, for he fears the curse Alberich placed on him when he violated his own rule of law.
Act I
A storm is raging. An exhausted man takes shelter and asks whose house he is in. Sieglinde brings him water and tells him that the house and she herself belong to Hunding. The stranger tells her he is wounded and unarmed. Sieglinde offers him mead, which he asks her to share. Revived, he prepares to go, saying that wherever he goes misfortune follows. Sieglinde begs him to stay, explaining that her life could not be unhappier than it is at the moment.
Hunding returns and offers the stranger grudging hospitality. He notices a resemblance between his wife and the stranger. Hunding asks his name. The stranger says it should be Woeful. He tells his tale. He and his father returned home from hunting one day to find their home destroyed, his mother murdered and his twin sister abducted. His father disappeared, and ever since he has been dogged by misfortune. He lost his weapons defending a girl who was being forced into a loveless marriage; he had killed her brothers only to see her killed by others of her clan. Hunding realizes that the murdered men were his kinsmen. Bound by the laws of hospitality, he gives the stranger shelter for the night but challenges his unarmed guest to a fight the next morning.
Alone, the fugitive recalls the sword his father once promised he would find in his hour of greatest need.
Sieglinde returns, having drugged Hunding. She recounts how, at her enforced wedding to Hunding, a stranger appeared and thrust a sword into the tree trunk. No-one has been able to pull it out. Sieglinde and the stranger now pledge themselves to one another and the stranger asks Sieglinde to rename him. Discovering his father's name was really Wälse, she is convinced he is her twin; she names him Siegmund and urges him to remove the sword from the tree. Calling it Nothung, he draws it out and claims Sieglinde as both bride and sister. Ecstatically and defiantly, they declare their love.
Act II
Wotan instructs Brünhilde, his favourite Valkyrie daughter, to ensure that Siegmund wins the fight with Hunding.
Wotan's wife Fricka announces that Hunding has appealed to her, as guardian of marriage, to punish the adulterous and incestuous couple. Wotan thinks they have done no wrong since they love one another: he has no regard for loveless bonds. Fricka demands to know how Wotan can both sanction incest and uphold the gods' laws. He outlines his plan: the gods need a hero, Siegmund, who is independent and can carry out the deeds they themselves cannot do. Fricka points out the folly of his argument: Siegmund owes his sword and life to Wotan; if he were truly independent he would not need the sword's protection. Defeated, Wotan promises that neither he nor Brünhilde will protect Siegmund.
Alone with Brünhilde, Wotan gives way to despair. He recounts now how, when the pleasures of love started to pall, he began to lust for power and was dishonest in his ruthless pursuit of it. Wotan tells Brünhilde the story of Alberich, the Nibelung who renounced love and stole the gold from the Rhinedaughters and made a ring from it. Wotan then stole it from Alberich, but instead of returning it to the Rhinedaughters he used it to pay the giants who built Valhalla. He tells her that Erda, source of all wisdom, is her mother. She and her eight Valkyrie sisters now gather up fallen heroes for Wotan, who believes they will protect him from Alberich. Determined that Alberich should never get the ring back, Wotan is desperate to seize it from the giant Fafner, who has transformed himself into a dragon. Wotan tells Brünhilde he cannot confront the giant himself because of their contract: he needs a free agent to act for him. When Brünhilde asks why Siegmund cannot be that hero, Wotan explains that Fricka saw through his plan; he has to abandon what he loves most. All he now desires is an end to his suffering. Wotan tells Brünhilde that she must not protect Siegmund and threatens the direst consequence if she disobeys.
Siegmund and Sieglinde are fleeing from Hunding. Sieglinde, wracked with guilt, tries to persuade Siegmund to abandon her but he vows to kill Hunding. Sieglinde faints. Brünhilde appears to Siegmund and announces that he will die in battle and join the other heroes in Valhalla. There he will meet his father. When Siegmund learns that he cannot take Sieglinde he refuses to go. He threatens to kill both Sieglinde and their unborn child rather than be separated from her. Brünhilde is astonished. Moved by compassion, she promises to safeguard Siegmund.
Hunding's horn is heard. Brünhilde tries to protect Siegmund but Wotan shatters Siegmund's sword with his spear. Hunding strikes Siegmund dead. Brünhilde gathers the pieces of the broken sword and flees with Sieglinde. Wotan annihilates Hunding and leaves in pursuit of Brünhilde.
Act III
The Valkyries gather dead warriors for Valhalla. Brünhilde arrives at great speed and the Valkyries are shocked to see that she is accompanied by a woman. Brünhilde begs the Valkyries to protect her and Sieglinde from Wotan. Terrified, they will not risk helping her. Sieglinde wants to die, but when Brünhilde tells her she is carrying Siegmund's son, who will be the noblest hero in the world, she begs protection. She is urged to flee to the forest in the east where Fafner guards the Nibelung hoard, and she leaves, taking with her the fragments of Siegmund's sword.
Wotan arrives and the Valkyries try to hide Brünhilde from his wrath, begging him to be merciful to her. Wotan is unmoved and denounces her disobedience, banishing her from Valhalla. She will be left to sleep until a mortal man wakes her. The Valkyries protest but they scatter when Wotan threatens them with the same fate.
Brünhilde asks Wotan if her crime deserves such a terrible punishment. When she felt compassion in the face of Siegmund and Sieglinde's love, she disobeyed Wotan but she believed it was what Wotan truly wanted. Wotan remains unforgiving, even when Brünhilde tells him that a Wälsung hero will be born to Sieglinde. Finally, Brünhilde asks to be surrounded by fire so that only a true hero will find her. Wotan agrees to this solution and bids her farewell. He calls on Loge, the god fire, to encircle her with flames.
