Baldr

Baldr is God of joy, light, purity, and the summer solstice. Baldr is son of Odin and Frigg. He has numerous brothers.

Hell
Because of Baldr's nightmares, his mother Frigg traveled the nine worlds and convinced each and every thing to swear an oath not to harm Baldr. The Gods made sport of testing Baldr's new safety. They threw darts and hacked with axes, but nothing could harm Baldr.

Loki was envious of Baldr. In the shape of an old woman, he learned from Frigg that she had missed one thing: the little harmless mistletoe bush. Loki found a mistletoe bush and turned a branch of it into a sharpened dart.

Returning to the company of the gods, Loki found them throwing missiles against Baldr in sport. To one side was Höðr, Baldr's blind brother. Loki asked Höðr why he wasn't joining in the sport. Höðr said he had no dart, nor could he see to shoot it. Loki gave Höðr the mistletoe dart, and guided Höðr's hand to throw the dart at Baldr.

The dart flew through the hall and struck Baldr. It pierced him and passed right through him. Baldr fell over on his face. He was dead. The grief of the Æsir was bottomless; their silence was deafening. Goddesses began to wail and weep. His wife Nanna died from grief when she heard the news. Óðin was the most affected, since he alone knew the extent of the loss they had suffered and the sorrow and pain that would follow his son's death.

Frigg begged for someone to ride to the kingdom of the dead, Hell, to bring Baldr back. Hermóðr, another of Óðin's sons, agreed to make the trip. Óðin provided his horse Sleipnir for the journey.

For nine nights, Hermóðr rode down the dark road to the land of the dead until he came to the bridge Gjallarbrú over the river Gjöll.

Soon Hermóðr approached the gates of Hell. He spurred Sleipnir on, and the horse jumped completely over the gate.

Hermóðr came to the hall of Hel. Hel was willing to release Baldr on the condition that all things in the world, living or dead, would weep for him. Should any creature refuse to weep, then Baldr must stay with Hel and never return to the Æsir. Hermóðr took his leave of Hel and bade farewell to Baldr and Nanna, who gave him many gifts, including Draupnir, to give to the Æsir.

On Hermóð's return to Ásgarð, the Æsir sent out messengers to all the nine worlds. All things did indeed weep for Baldr: men and beasts, stone and metal, in the way that these things weep when they are covered with frost and begin to thaw.

Except for… Loki.

Resources

 * http://www.hurstwic.org/history/articles/mythology/myths/text/baldr.htm