The three Norns try to arrange the past, present and future into a single story. They recount how Wotan broke off a branch from the Sacred Ash which became the shaft of his spear. As a consequence, the ash withered and the wellspring of wisdom ran dry. Thus, their attempt to spin the myth’s various images into one narrative thread fails. When they seek to tell how Alberich stole the Rhinegold and forged it into a ring, the thread finally snaps, marking the end of eternal knowledge. After she has made him promise not to forget her story, Brünnhilde sends Siegfried into the world as her hero. Siegfried tells her how he came by the ring, which he leaves her as a token of his love. As they bid each other farewell, she gives him her horse Grane to accompany him on his travels.
Hagen tells his half-siblings Gunther and Gutrune how Siegfried seized the Nibelung treasure and that Brünnhilde is held captive on a flame-encircled rock. To make it easier for Gutrune to win Siegfried’s heart, a forgetfulness potion will erase every female image from his memory. They will have to persuade Siegfried that, to earn the right to take Gutrune as his wife, he will first have to go through the fire and rescue Brünnhilde who will then become Gunther’s bride. At this moment, Siegfried appears. Hagen explains to him the capabilities of the cloaking helmet, which Siegfried seized along with the ring: It enables the wearer to adopt any guise. The siblings are persuaded by Hagen’s tale and Gutrune hands Siegfried the potion. No sooner has he downed the contents of the cup than he agrees to the deal.
Absent-mindedly reminiscing, Brünnhilde is looking at the ring when Waltraute arrives. The Valkyrie sister gives her the news about their father Wotan: He has ordered the pieces of the felled Sacred Ash to be piled up around the fortress of the gods at Valhalla and is waiting for the age of the gods to come to an end. She pleads with Brünnhilde to return the ring to the Daughters of the Rhine. But Brünnhilde clings to the image of Siegfried’s love and sends Waltraute away. Hearing the sound of a horn, Brünnhilde believes Siegfried to have returned. However, the man coming towards her bears little similarity to her recollection of him. When she asks who he is, he replies, “A Gibichung am I and Gunther is the hero whom, woman, you shall now follow.” She hopes to defend herself by using the ring’s power, but the intruder tears it from her finger. He then makes clear his intention to have her as well. “Trembling and with wavering steps she goes into the cave.”
Hagen appears to be fast asleep. The voice of his father Alberich counsels him, once Siegfried has slain the dragon, broken Wotan’s spear and seized the ring, the hero himself must be eliminated for the ring to be Hagen’s. Siegfried enters and reports on his successful conquest of Brünnhilde. Gutrune questions him warily, but he dispels any suspicion that he may have had his way with Brünnhilde. Hagen calls the men to arms, only to inform them that a double wedding is planned. When Gunther enters with Brünnhilde at his side, she is incredulous that Siegfried is to be married to Gutrune. She recognises the ring that was taken from her on Siegfried’s hand and declares that she is pledged not to Gunther but to Siegfried! He contests this, swearing an oath on the point of Hagen’s spear. Brünnhilde accuses him of swearing falsely. Hagen offers to be Brünnhilde’s avenger and is able to glean information from her concerning Siegfried’s vulnerability. He subsequently persuades Gunther that only Siegfried’s death can salvage the honour of the Gibichung race.
Out hunting, Siegfried meets the Rhine Daughters. When they demand he give them the ring he is unwilling to hand it over. They proceed to foretell his imminent death that very day. However, he does not believe the river maidens. Gunther and Hagen arrive along with their entourage. Siegfried tells the story of his encounter with the Forest Bird. Hagen interrupts him, inviting him to take a drink to help refresh his memory. At once images flood back of his initial encounter with Brünnhilde and he talks of their first kiss. Hagen stabs him in the back with his spear because it is now clear that Siegfried lied when he took the oath. One last time, Siegfried sees Brünnhilde’s image clearly before him. Gutrune is awaiting Siegfried’s return with increasing unease when Hagen and Gunther arrive. Hagen presents Siegfried’s death as revenge for his broken oath and demands the ring as reparation. Brünnhilde takes the ring and orders a pyre to be built upon which she wishes to be burnt alongside Siegfried and Grane. She looks back on her story for the final time. Reflecting in the water: the ring.