Siegmund, wounded, had been fleeing pursuers; he saw a hut and took refuge inside. The hut had been built around a living tree. Soon Sieglinde came home and detected Siegmund's presence. She was the wife of Hunding, the owner, a cruel man whom she despised.
The tree contained an imbedded sword, high up on its trunk, that no one had ever been able to extract.
Siegmund explained that he had been wounded in a scuffle after his spear and shield were smashed. Sieglinde urged him to stay and await the return of her husband.

Siegmund told his story, while being served a meal with Hunding. As a child, his mother had been slain, and his sister had been carried off. His father had mysteriously vanished.
[Quibble: We are clueless about what happened here. Who were these enemies? Was the fire started by Loge, under orders from Fricka, or even Wotan himself?]
During the meal, Siegmund realized that the enemies he had fought earlier in the day had been Hunding's relatives, so Hunding had sworn to fight him to the death in the morning.
Sieglinde drugged Hunding so he would sleep late. She and Siegmund fell in love, despite having discovered that they were actually brother and sister.

Siegmund and Sieglinde did not realize that Wotan was their true father, by way of a mortal woman, and that they had been conceived as part of a plan to retrieve the Ring. It was Wotan who had driven the sword, called Nothung, into the tree years ago, in anticipation of Siegmund's needs.
Many had tried to extract the sword from the tree, without success, over the years. Siegmund was quite surprised to discover that he was the chosen one, as a light tug pulled the sword free.
Siegmund and Sieglinde fled together from Hunding, into the night.
Brünnhilde was a Valkyrie, who, on her horse Grane, carried fallen heroes of battle to Valhalla. She was one of Wotan's many daughters by the goddess Erda.
As Siegmund and Sieglinde fled, Wotan ordered her to protect Siegmund in the coming fight with Hunding.
Wotan's plan to retrieve the Ring seemed to be working.
Wotan's wife, Fricka, confronted him in a rage. She had never been consulted about this plan, which she saw as a thinly-veiled attempt to get the Ring back. Siegmund could only triumph if Wotan so-willed it.
As the goddess of the sanctity of marriage, she found the couple to repugnant on three counts: Sieglinde had just abandoned her husband, Siegmund had abandoned his wife (not mentioned in the opera,) and the two of them had a serious incestuous romance.
Fricka demanded that Wotan uphold his own law; Siegmund had to die!
Brünnhilde met again with her father, who countermanded his previous order to save Siegmund. She now had to make sure that Siegmund died! Wotan gave her contradictory commands: his words said kill Siegmund, but his body language told her to save Siegmund.
Brünnhilde was personally torn and anguished. She waited for Siegmund and Sieglinde. Once they appeared, she revealed herself and told Siegmund to prepare for death.
She felt sorry for them; she changed her mind and decided that she would save Siegmund, in defiance of her father. However, Wotan appeared and shattered the sword Nothung upon his spear, allowing Hunding to kill Siegmund.
Brünnhilde carried Sieglinde with her, as Grane flew them to the Valkyrie mountain. Her father angrily pursued.
Now came the famous Ride of the Valkyries, as the sisters all converged on Valkyrie mountain. Some of them even carried the corpses of fallen heroes.
[Quibble: I guess we will never get to see the famous Ride of the Valkyries, with the women flitting through the air upon mechanical horses. Apparently, it has become too expensive for opera houses to do this, so we have to settle for a lot of pointing into the air, instead.]
Brünnhilde had not yet arrived; they all wondered what had happened.
Brünnhilde finally arrived, unexpectedly carrying Sieglinde, who was pregnant with a great future hero. She asked her sisters to help and protect her.
The Valkyries refused to help Brünnhilde, but they did advise Sieglinde to flee into the forest to the East, near where Fafner guarded the Ring and the hoard.
A great storm came to the mountain, and Wotan arrived in an unreasonably enraged mood. He sent Brünnhilde's sisters away, so that he could personally concentrate on her punishment.
Wotan had an anger-management problem, since he was totally unable to see that he had given Brünnhilde mixed messages; he instead viewed his verbal commands as law.

Wotan decreed his punishment: Brünnhilde would be be placed in an enchanted sleep, awaiting the appearance of the first mortal man, who would make her his mortal wife.
[Quibble: This is a really strange form of punishment, probably found only in mythology; why not just banish her, instead?]
Brünnhilde pleaded for extra conditions, that she was to be surrounded by fire, that only a worthy hero could breach the flames.
Wotan agreed to these conditions, and he commanded that Loge appear to surround the mountain in flames.
No singer played the part of Loge in this opera; Loge was solely represented by the appearance of the flames.

As Brünnhilde fell into deep sleep, Wotan sneakily issued another condition, that no hero could ever pass who feared his spear point. Wotan sensed that the conditions of Brünnhilde's punishment might create problems for him in the future.
Wotan sadly departed, realizing that he would forever be apart from his beloved daughter.
As night fell, Brünnhilde began her long sleep, awaiting the appearance of the hero who would awaken her.
However, Brünnhilde was not alone in her sleep; for around the corner, also slept Grane, her faithful horse.

Die Walküre Libretto

Siegfried