The Three Rhinemaidens are singing and swimming in the River Rhine, as Siegfried arrives. He is hunting, but has lost his prey. The Rhinemaidens spot the Ring and try to persuade (almost seduce) Siegfried into giving it to them. For a moment Siegfried holds the Ring in the air and is indeed going to give it away, but as the Rhinemaidens warn him of the dangers which he will meet if does not yield the Ring, he simply declares he does not care for his life. The Rhinemaidens swim away calling him a madman - and they prophecy that the Ring will today go to a certain lady, who make a more reasonable decision. Siegfried ignores them: first seducing, then threatening, but it did not work - not for him.
Siegfried meets the rest of the hunting party: Hagen, Gunther and some vassals. Gunther is very depressed as Hagen mixes a drink for Siegfried, who also offers the drink to Gunther. To brighten Gunther, Siegfried decides to tell a story from the years when he was but a boy. He now remembers Mime and how he could understand the bird which told him not to trust Mime - and how he eventually slaughtered Mime. Hagen gives him another drink which will "waken [his] memory more clearly". Now Siegfried tells the others how he found Bruennhilde - Gunther is shocked: Siegfried remembers now everything [and what's more, his beloved turns out to be none other than Bruennhilde - Gunther may not have suspected this earlier]! Two ravens fly up and circle above Siegfried, then fly away. Hagen asks him if he was able to understand what the ravens said. Revenge they cried to me, says Hagen, and plunges his spear in Siegfried's back. Siegfried falls down. Gunther and the vassals are terrified and ask Hagen what did he do that for. Hagen still maintains it was a vengeance. Siegfried opens his eyes and still sees a vision of Bruennhilde, then dies.
Siegfried's corpse is taken to the hall of the Gibichungs. Hagen tells Gutrune that Siegfried has fallen prey to a wild boar. Gutrune accuses Gunther of murdering Siegfried, but Gunther replies that Hagen was the "wild boar". Hagen confesses murdering Siegfried, but as Gunther proceeds to take the Ring, he attacks Gunther and strikes him dead, saying abruptly: "Give the Ring here!". Now everyone present is shocked, as Gunther is killed by his own half-brother. Nobody makes any attempt to stop Hagen as he now proceeds to take the Ring - but miraculously Siegfried's corpse raises its hand as Hagen draws near. Hagen is terrified and dares not go any nearer.
Now Bruennhilde enters: she has heard everything and now knows what all was about. She makes it clear that Siegfried belonged to Bruennhilde all the time and Gutrune admits that.
Bruennhilde instructs the vassals to pile logs into a funeral pyre and leave Siegfried's corpse atop the pyre. She understands that it was not in fact Siegfried who deceived her as he in turn was betrayed himself and thus forgives Siegfried and mourns her loss. She wishes him peace saying that she knows now everything. She takes the Ring and says that the fire that soon consumes her will cleanse it from the Curse and then the Rhinemaidens can fetch their gold from the ashes. She puts on the Ring and takes a torch from one of the vassals. She tells Wotan's ravens to fly home past the Valkyrie Rock and bid Loge, who is still there, to go to Valhalla: the downfall of gods is nigh. He hurls the torch into the pyre with the words "Thus do I throw this torch at Valhalla's vaulting towers!" (DG translation). The wood catches fire rapidly. Bruennhilde mounts her steed, Grane, and speaking a last greeting to Siegfried she rides into the blazing pyre.
"The flames instantly blaze up and fill the entire space before the hall, seeming even to seize on the building. In terror the women cower towards the front. Suddenly the fire falls together, leaving only a mass of smoke which collects at back and forms a cloud bank on the horizon. The Rhine swells up mightily and sweeps over the fire. On the surface appear the three Rhine-daughters, swimming close to the fire-embers. Hage, who has watched Bruennhilde's proceedings with increasing anxiety, is much alarmed on the appearance of the Rhine- daughters. He flings away hastily his spear, shield and helmet, and madly plunges into the flood crying 'Keep away from the Ring!'
"Woglinde and Wellgunde twine their arms round his neck and draw him thus down below. Flosshilde, swimming before the others to the back, holds the recovered Ring joyously up.
"Through the cloud-bank on the horizon breaks an increasing red glow. In its light the Rhine is seen to have returned to its bed and the nymphs are circling and playing with the Ring on the calm waters.
"From the ruins of the half-burnt hall, the men and women perceive with awe the light in the sky, in which now appears the hall of Valhalla, where the gods and heroes are seen sitting together.... Bright flames seize on the abode of the gods; and when this is completely enveloped by them, the curtain falls." (Wagner's stage directions)