'Das Rheingold' is the first part of Wagner's 'Ring Cycle'.
Alberich, a gnome of the Nibelung, discovers the all-powerful Rhine Gold and fashions a ring out of it, knowing that whoever wears it will rule the world, but must renounce love. The gods Wotan and his wife Fricka have build a new castle and paid the giants by promising them Fricka's sister Freia, who grows the golden apples that give the gods their power. After a struggle, she is kidnapped and all the gods begin to age and weaken. To get her back they decide to steal the Ring and bargain with the giants.
br>Meanwhile Alberich has been forcing others to mine gold and Mime makes a helmet, the 'Tarnhelm', out of it, thinking this will help him seize the Ring. Alberich steals the Tarnhelm but the gods arrive and trick both it, the Ring and his gold out of him, taking him prisoner. In a fury he curses the Ring to bring death and envy to all who posess it.
The gods use the Ring and helmet to bargain with the giants. They win Freia back and go home to their new castle, but as they leave the giant Fafner murders his brother Fasolt to claim the ring, continuing its bloody history...