After _Siegmund's_ death _Sieglinde_ gives birth to _Siegfried_, a son of their illicit union, who is reared by one of the Nibelungs, _Mime_, in the forest where _Fafner_ guards the Nibelung treasure. _Mime_ is seeking to weld the pieces of _Siegmund's_ sword (Nothung or Needful) in order that _Siegfried_ may slay _Fafner_, _Mime_ hoping then to kill the youth and to possess himself of the treasure. But he cannot weld the sword. At last _Siegfried_, learning that it was his father's weapon, welds the pieces and slays _Fafner_. His lips having come in contact with his bloody fingers, he is, through the magic power of the dragon's blood, enabled to understand the language of the birds, and a little feathery songster warns him of _Mime's_ treachery. _Siegfried_ slays the Nibelung and is then guided to the fiery barrier around the Valkyr rock. Penetrating this, he comes upon _Brünnhilde_, and enraptured with her beauty, awakens her and claims her as his bride. She, the virgin pride of the goddess, yielding to the love of the woman, gives herself up to him. He plights his troth with the curse-laden ring which he has wrested from _Fafner_.
_Siegfried_ goes forth in quest of adventure. On the Rhine lives the Gibichung _Gunther_, his sister _Gutrune_ and their half-brother _Hagen_, none other than the son of the Nibelung _Alberich_. _Hagen_, knowing of _Siegfried's_ coming, plans his destruction in order to regain the ring for the Nibelungs. Therefore, craftily concealing _Brünnhilde's_ and _Siegfried's_ relations from _Gunther_, he incites a longing in the latter to possess _Brünnhilde_ as his bride. Carrying out a plot evolved by _Hagen_, _Gutrune_ on _Siegfried's_ arrival presents to him a drinking-horn filled with a love-potion. _Siegfried_ drinks, is led through the effect of the potion to forget that _Brünnhilde_ is his bride, and, becoming enamoured of _Gutrune_, asks her in marriage of _Gunther_. The latter consents, provided _Siegfried_ will disguise himself in the Tarnhelmet as _Gunther_ and lead _Brünnhilde_ to him as bride. _Siegfried_ readily agrees, and in the guise of _Gunther_ overcomes _Brünnhilde_ and delivers her to the Gibichung. But _Brünnhilde_, recognizing on _Siegfried_ the ring, which her conquerer had drawn from her finger, accuses him of treachery in delivering her, his own bride, to _Gunther_. The latter, unmasked and also suspicious of _Siegfried_, conspires with _Hagen_ and _Brünnhilde_, who, knowing naught of the love-potion, is roused to a frenzy of hate and jealousy by _Siegfried's_ seeming treachery, to compass the young hero's death. _Hagen_ slays _Siegfried_ during a hunt, and then in a quarrel with _Gunther_ over the ring also kills the Gibichung.