Das Rheingold is the first in the cycle of four operas entitled Der Ring des Nibelungen, written and composed by Richard Wagner. It is a prequel to the other three (Die Walküre, Siegfried and Götterdämmerung), which carry the main part of the plot.
The opera comprises a single, continuous Act in four scenes: Scene One is laid at the bottom of the river Rhine, Scene Two on a mountaintop above the Rhine, Scene Three in an underground cavern in Nibelheim. For Scene Four we return to the mountaintop of Scene Two.
The music opens with a most extraordinary Prelude – 136 bars that build and play with just the notes that form the chord of E flat major. The lack of any modulation already gives us a sense of tension. As the curtain rises, we see three Rhine Maidens, swimming and playing in the water at the bottom of the river. The long-awaited modulation finally occurs, and they sing happily about their task as guardians of the Rhine Gold. They are watched lustfully by an ugly dwarf, Alberich, who lives in the underground world of Nibelheim.
The Rhine Maidens tease Alberich who tries to catch each of them in turn, but they evade his grasp, enraging him. A bright sunbeam illuminates the gold treasure and we hear on the trumpet the important Gold motif that will recur throughout the entire cycle. Alberich catches sight of the gold and the Rhine Maidens foolishly tell him of its secret power – whoever can make a ring from the gold, and who also renounces love, will become all-powerful and immeasurably wealthy. Suddenly, Alberich snatches the gold, utters a curse on love, and disappears below the riverbed, taking the gold with him as the scene starts to change.
As the scene clears, we see a magnificent, newly-built castle on a mountaintop way above the river. As the castle becomes visible, we hear in the brass for the first time the Valhalla motif. The castle has been built by two giant brothers, Fasolt and Fafner, for Wotan, chief of the gods, and his wife Fricka. She has long been nagging Wotan for it, although her motive for doing so is to try to keep him at home more, and stop his wanderings in the pursuit of other women. However, the price he has agreed to pay the giants for their work is to give them Fricka's sister, Freia.
When he made the bargain, he had no intention of fulfilling it, and sent Loge, the god of fire and cunning, off to find a way of wriggling out of it; Loge has not (so far) re-appeared. Freia is vitally important to the gods; she tends the orchard in which grow the golden apples that are the secret of the gods' eternal life. The giants arrive and demand payment for their finished work. Wotan insists that they must find an alternative reward. No surprisingly, the giants are angry that he should now renege on the deal, and are about to carry Freia off by force when Donner and Froh, the gods of thunder and the rainbow, arrive to protect their sister. A right godly battle looks inevitable, but Wotan spots Loge approaching from a distance.
Loge enters to his own orchestral motif and dismays Wotan by announcing that he only promised to try to find an alternative solution, and that the giants' workmanship is faultless, so the debt should be paid. However, this is Loge, the god of cunning. He also tells Wotan that Alberich has stolen the Rhine Gold and that the Rhine Maidens have asked Wotan for his help in recovering it. Fasolt and particularly Fafner, hearing about the gold, are hooked, and they begin to covet the treasure.
Everyone now has their own motive for wanting the cursed gold – Fricka believes that her possession of the Ring will ensure Wotan's fidelity, Donner points out that if Alberich has the Ring, he will have dominion over the gods. Wotan decides he must have the gold himself and refuses the new deal with the giants, at which point they snatch Freia as ransom, giving Wotan until the evening to decide. Wotan tells Loge to accompany him to Nibelheim to recover the gold. During an orchestral interlude, they descend from the mountaintop and we hear the sound of hammering on tuned anvils as the scene changes.
Alberich has now made a Ring from the gold and has used its power to enslave the other Nibelungs. As the scene opens, he is chastising his brother Mime, who has been making a helmet, a Tarnhelm, which will enable its wearer to be invisible or to take on any form he wishes. Mime tells him that it is finished and Alberich puts it on. Now invisible, he beats the defenceless Mime, before leaving, delighted in his latest power. Wotan and Loge enter and commiserate with Mime. Alberich returns and, being suspicious, asks Wotan and Loge what they want. Loge says that they have heard rumours of the happenings in Nibelheim and have come to see for themselves.
Alberich boasts of his power and wealth, which are growing daily, and mentions the Tarnhelm. A plan forms in Loge's mind to trick Alberich. Alberich demonstrates the helmet's powers by turning himself into a giant serpent. Loge appears suitably impressed and asks whether, as well as large, terrifying things, the helmet can change him into small things. To demonstrate, Alberich turns himself into a toad, at which point Wotan puts his foot on him and removes the helmet. Alberich immediately returns to normal size, is captured by Wotan and Loge and taken prisoner. Together they hurry back to the surface and on above.
The scene returns to the mountaintop and the new castle. Wotan and Loge enter with Alberich firmly bound. He is told that the price for his freedom is not only the Rhine Gold, but also the treasure he has been forcing the slave Nibelungs to gather for him. Alberich agrees since he believes that by retaining the Ring he can replace it, and summons the Nibelungs to bring up the treasure. Alberich demands the return of the Tarnhelm from Loge but he is refused. Loge then asks Wotan if he can now let Alberich go. Wotan demands that the Ring on Alberich's finger be added to the rest of the gold. Alberich vehemently refuses and Wotan is forced to tear it from his finger. Before he leaves, Alberich, to the accompaniment in the orchestra of a new Curse motif, curses the Ring, prophesying that its magic will bring death to whoever possesses it.
Donner, Froh and Fricka now return, followed soon after by Fasolt and Fafner who are bringing back Freia. Fasolt insists that his grief at losing Freia will only be assuaged if the pile of gold is big enough to hide her completely. All the treasure is piled up and Fafner wants the Tarnhelm added to the top of the pile to hide her hair. Fasolt, for his part, insists that her eyes are still visible through a chink. Despite the fact that all the gold has been used, Fafner insists that the chink be filled, and demands the Ring from Wotan's finger. When Wotan refuses, Fasolt reverts to the original bargain and makes to carry off Freia again. They all now turn on Wotan and insist he give up the Ring, but he still refuses. Just then, Erda, the Earth goddess, appears and solemnly warns Wotan of dire consequences should he not give up the cursed Ring – Wotan relents.
Fafner spreads out a huge sack and prepares to divide the gold, but not equally. When Fasolt objects, he argues that Fasolt would have preferred to keep the girl and would not have shared her; therefore, he, Fafner deserved the greater part. The giants fight and Fafner kills Fasolt with a single blow. Already, the Curse of the Ring has gained its first victim. Fafner collects all the gold, including the Ring, and makes off with it. Fricka suggests they enter the new castle. Wotan, now beginning to see the course of events he has set in motion, says 'With unclean wages I paid for that building', and decides that he must consult Erda. Donner determines to clear the air with a thunderstorm and a rainbow is seen forming a bridge into the castle. Wotan names the castle Valhalla. When Fricka asks what it means, Wotan mysteriously answers that his courage, if it lives, will make the meaning plain. All except Loge enter the fortress castle across the rainbow. From below is heard the lament of the Rhine Maidens at their loss, and the curtain falls to a magnificent D flat orchestral Coda.