The Ring Cycle, a lengthy tale of epic adventure, can be summarized as follows:
Das Rheingold introduces the ring. The well-known prelude opens with 136 measures of an E-flat major chord: this prolonged harmony represents the ageless river Rhine, upon whose banks the Rhinemaidens play. Alberich, a Nibelung dwarf, tries vainly to seduce one of the Rhinemaidens. Mockingly, they reveal the secret of the gold they guard: out of it, one can forge a ring powerful enough to rule the world, provided the forger gives up Love forever. Alberich manages to steal the gold and makes the ring, using it to control his fellow dwarfs while he plans his world take-over. In the meantime, Wotan (king of the gods), like many new home owners, has to figure out how to finance the construction of Valhalla (hall of the gods). He has promised his sister-in-law as payment to the construction workers, but his wife Fricka isn't too keen on selling her sister to the giants (led by Fafner). Loge (god of fire) tricks Alberich into turning himself into a toad and brings Alberich back to Wotan, who takes the ring from the dwarf. Bitter at losing his ring, Alberich places a curse on it: lack of the ring will fuel desire for it and possession will only lead to misery. Wotan ends up giving the Ring to Fafner as ransom for Fricka's sister.
Die Walküre introduces the twin siblings Siegmund and Sieglinde. Fleeing for his life, Siegmund seeks shelter at Sieglinde's house. Her husband Hunding happens to be one of Siegmund's pursuers, and the two of them must cross swords the next day. Siegmund laments his lack of a weapon, but Sieglinde directs him to the sword Nothung stuck in an ash tree. Despite discovering their familial ties, the two fall in love. Since he is actually the twins' father, Wotan sends his Valkyrie daughter Brünnhilde to aid Siegmund. Fricka protests, and Wotan uses his spear to break Siegmund's sword during the battle. Siegmund is slain, but Brünnhilde rescues both the sword fragments and Sieglinde (who is pregnant with Siegmund's child Siegfried). Wotan is angry that she intervened, but since Brünnhilde is his favorite child, he merely strips her of immortality and sends her into an enchanted sleep, surrounded by fire.
In Siegfried, Alberich's brother Mime raises the orphan Siegfried, hoping that Siegfried will kill Fafner and enable Mime to gain the ring. Mime attempts unsuccessfully to reforge the Nothung. Fulfilling prophecy, Siegfried reforges the sword himself and kills Fafner, who has the form of a dragon. When he accidentally tastes the dragon's blood spilt on his hands, Siegfried understands the song of a woodbird, who instructs him to take the Ring from Fafner. Reading Mime's thoughts of betrayal, Siegfried kills the dwarf as well. The woodbird also informs Siegfried of a mysterious woman asleep in the midst of fire, and Siegfried sets off to find her. After defeating a disguised Wotan and breaking his spear, Siegfried successfully awakes Brünnhilde, and the two fall in love.
In Götterdämmerung (Twilight of the Gods), Gunther, the lord of the Rhine people, gives Siegfried a love potion that causes Siegfried to forget Brünnhilde and fall in love with Gunther's sister Gutrane. Siegfried has given Brünnhilde the Ring as a token of their love, but her Valkyrie sister urges her to destroy it, because their father Wotan has lost his spear and power and is hiding out in Valhalla. Instead, Brünnhilde keeps it, and under the influence of the potion, Siegfried steals it from her. Enraged, Brünnhilde helps Alberich's son murder Siegfried, but Siegfried's memory returns, and he dies thinking of Brünnhilde. Brünnhilde repents and orders a funeral pyre to be built. She rides into the fire herself, and the Rhinemaidens get the ring back. The story closes with flames flickering about Valhalla in the background.