The Rhinegold harbors a deep magic in it. Anyone who should make a ring from it could rule the whole world, but the smithy that creates it has to renounce love forever. When Wotan, the ruler of the Gods, finds out that the Rhinegold has been stolen from the protection of the Rhinemaidens by the dreadful nibelung Alberich, he sees an opportunity. Wotan had promised the giants Fasolt and Fafner the goddess Freia (his wife’s sister) in payment for them building Valhalla, but now that they all know the power of the gold, the giants ask him to retrieve that instead. Loge, a demigod, who brought the news of the theft to Wotan thinks that Alberich might have already created the ring, and, if so, would be more powerful than all the Gods. The thought of being under someone else’s power terrifies them, as does the realisation that if the giants take Freia, their eternal youth will also fade. Wotan must retrieve the Rhinegold and asks Loge to show him the way.
Loge was right. Alberich has fashioned a ring from the Rhinegold, and has made himself ruler of the Nibelungs, the dwarves that live in the mountains. He forces them to mine for more Rhinegold, and to make more magical items for him, including the Tarnhelm, a headpiece which makes its wearer invisible. As they descend into the mountain, Wotan and Loge are disgusted by the wretched state of this once happy kingdom. When Alberich boasts of his power by transforming himself into a serpent and back again, Loge seizes on an idea. He asks if Alberich can transform himself into a toad, and when he obliges, they grab him and tear the Tarnhelm from his head. They take him captive and demand that he hand over all of the Rhinegold, including the ring. Alberich tears the ring off his finger, and mutters a curse over it, which will play itself out several times before the end of the tetralogy: the ring will only bring misery and murder, and whoever wears it will be its slave.
Wotan takes the gold, as promised, to Fafner and Fasolt, but they refused to return Freia unless every last piece, including the ring, is included. As Wotan resists giving them the ring, the earth opens and Erda, the mother of the earth, rises up. She warns Wotan to give the Ring away, lest darkness and despair shall cover the earth. Wotan reluctantly throws the ring onto the pile of gold, and Freia is returned to him. But, Alberich’s curse takes its first victim: unable to decide who should keep the ring, Fafner murders his brother.
The first of Wagner’s tetralogy Der Ring des Nibelungen, Das Rheingold establishes the power and the curse, surrounding the ring made from Rhinegold, which continues to plague both gods and mortals through the next three operas Die Walküre, Siegfried, and Götterdämmerung.