Wotan exhorts his daughter Brünnhilde, a Valkyrie, to protect his mortal son Siegmund in his coming duel with Hunding. Wotan had been grooming Siegmund to be a “free hero”—a free-willed mortal unaided by the gods, unbound by Wotan’s treaties, and consequently the only one capable of regaining the cursed Ring that Wotan was earlier forced to yield. But Fricka, Wotan’s wife and the protector of marriage, is outraged at the adulterous and incestuous love of Siegmund and Sieglinde and forces Wotan to let Hunding triumph. Wotan changes his order to Brünnhilde and tells her that she must let Siegmund die in combat.
Siegmund and Sieglinde rest during their flight. While Sieglinde sleeps, Brünnhilde appears to Siegmund, instructing him to follow her to Valhalla after his death. Deeply moved by Siegmund’s devotion to Sieglinde, Brünnhilde decides to disobey her father’s orders and save Siegmund’s life. After Hunding arrives and begins his battle with Siegmund, a furious Wotan appears and shatters Siegmund’s sword.
Allowing Hunding to easily kill Siegmund, Wotan then strikes Hunding down as well. Having defied her father, Brünnhilde gathers up the broken pieces of the sword and flees with Sieglinde to safety.