Siegfried, the son of Siegmund and Sieglinde, has been brought up by his foster-father Mime, brother of Alberich the Nibelung. For Mime, Siegfried is simply the means to kill the dragon Fafner, to gain the Ring for himself. The only weapon powerful enough to kill Fafner is the sword Nothung, shattered by Wotan on Siegmund’s death. And Mime is unable to re-forge the sword.
Siegfried’s childhood has been wild, free and fearless, and there is no affection between him and Mime. Siegfried cannot believe that Mime is his true father, and Mime, under duress, is obliged to tell him the truth about his parentage, showing him the fragments of the sword. For Siegfried the sword will be his passport to freedom, and he demands that Mime repair it, and goes out.
An unexpected visitor to Mime’s cave arrives: it is the Wanderer (Wotan in his self-imposed exile from Valhalla). Mime refuses hospitality, and the Wanderer challenges him to a contest of wits: he will answer Mime’s questions, or forfeit his head. But Mime is more inspired by his own intended ingenuity, than with finding out what he really needs to know. Wotan, having answered his questions, turns the tables on him: Mime cannot say who will forge the sword Nothung on which his plans depend. The sword, says the Wanderer, will be forged only by one who knows no fear, and Mime’s life will be forfeit to him. Siegfried returns, and realising that Mime is incapable of forging the sword, he gets on with it himself. Mime, seeing the Wanderer’s prophecy coming true, realises that he is in deep trouble while Siegfried remains fearless. Mime plans to teach Siegfried fear by leading him to Fafner, the most fearful thing he can think of. But here lies another dilemma: if Siegfried is afraid of Fafner, he won’t be able to kill him – how then would Mime get the Ring, without Siegfried unwittingly doing so for him? While Siegfried forges the sword, Mime prepares a poisoned drink with which to tempt Siegfried, after the Ring is won.
The Wanderer’s next encounter is with his old adversary Alberich, who has kept an obsessive guard outside Fafner’s cave. Alberich’s desire for power, and his hatred of Wotan, are undiminished.
The Wanderer however, seeing that events are of their own accord going the way he desires them to go, is unperturbed. He goads Alberich by calling up Fafner to warn him of danger; Fafner is sleepy and unimpressed.
Mime brings Siegfried to Fafner’s lair, and leaves him there to await developments. With any luck they will kill each other – if not, then he has a plan in hand.
Siegfried is relaxed – the woods are good to him, and a bird is singing. He imagines it has something to tell him, and tries to understand it; in the process he unwittingly wakes Fafner, who is hungry. Siegfried kills Fafner. As he withdraws the sword from Fafner’s heart the blood spurts over his hand, and he tastes it. Suddenly he can understand the Woodbird, who tells him of the treasure in the cave and then of Mime’s treachery. Siegfried enters the cave, returning later with the Ring and Tarnhelm. Mime returns to deal with Siegfried. For the first time in his life Siegfried understands his motives clearly and kills him with one deadly blow. The Woodbird now tells Siegfried of a beautiful woman, lying asleep, surrounded by fire. This is Brünnhilde, and he sets off after the bird to find her.
The Wanderer’s third encounter is with Erda, mother to his daughter Brünnhilde, whom he wakens from a deep sleep below the earth. He needs her reassurance as to the outcome of the rolling events.
The Wanderer leaves Erda and meets Siegfried on his way up the mountain. Siegfried does not know who he is, and is impatient and aggressive with the old man barring his way. The Wanderer hopes for the young man’s understanding, but is finally coerced into challenging him. Siegfried shatters his spear, leaving the Wanderer broken and powerless.
Siegfried continues through fire to find Brünnhilde. He is overwhelmed by her: the one who knows no fear finally discovering its meaning. Regaining his composure, he awakens her. Overjoyed to learn that it is Siegfried who has woken her, Brünnhilde soon realises that earthly love means an end to her immortality. She resists – but finally embraces her fate, her new life as a mortal, and a new dawn of hope.