The Ring of the Nibelung was a ring of pure gold purported to wield great power at the cost of cursing the owner with great disaster. The Nazis knew of the story and occupied Neuschwanstein Castle in the German Alps where the ring was located to take possession.
Indiana Jones, following up a legend that Mad King Ludwig — who built the castle with a love of The Ring — had a passion that stemmed beyond Richard Wagner's work, infiltrated Neuschwanstein with his associate Jack.
In the castle's cellars, Jones found the Ring of the Nibelung inside a secret chamber. When he reached out to take it, the artifact attached itself to his finger and the archaeologist was unable to remove it. Neuschwanstein Castle began to shake when the two men moved away from the chamber and their presence discovered by the Nazis forced them to flee. The ring provided its own illumination in their getaway vehicle but the castle started to collapse in their wake.