Asgard's trickster God, Loki, gets captured by a nasty giant named Geirrod. He makes a deal with the bad guy: He promises to lure the mighty Thor to Geirrod's hall without his weapons if Geirrod sets him free. Back in Asgard, he tricks Thor into making the trip.
On the first night, Thor and Loki make a stopover at the home of the giantess Grid, who warns Thor that Geirrod is a crafty little bugger and loans him her magic protective belt, iron glove, and staff. The next day, Thor and Loki almost drown downstream of Geirrod's very full-bladdered daughter, but finally, they arrive in Geirrod's digs.
After crushing Geirrod's two daughters with his chair (long story) Thor agrees to play a game with the giant: tossing a molten iron back and forth. Since Thor has an iron glove and Geirrod doesn't, Thor wins. He sends the molten iron straight through Geirrod's midsection, ending the giant's life—and this story.
The Less Short Story
One day, just for a lark, Loki decides to disguise himself as a bird using Freyja's magical feather dress.
He's apparently never heard that old saying about the cat, because just for curiosity's sake, Loki decides to check out the goings-on in the hall of a giant named Geirrod.
When Geirrod notices the strange bird perched in his rafters, he orders his men to catch it.
Loki's perched pretty high up there, so the first man who attempts the climb huffs and puffs and can't quite reach him.
Because he's enjoying watching this guy's struggle, Loki decides not to fly away until he's seen the second guy attempt to scale the wall, too.
The second guy turns out to be a much better climber than the first. He gets within arm's reach of Loki.
When Loki tries to take flight, he discovers his feet are stuck to the rafters (we smell magic here).
Freyja's magical feather-dress is apparently not that great a disguise, because the minute Geirrod gets a close look at the "bird," he's pretty sure it's really a person in disguise.
Loki's keeping mum, though, so Geirrod locks him in a box without food and water to try and loosen his tongue.
It works. After three months in the box without food and water, Loki's eager to talk.
Loki wants to be released. Geirrod wants Thor in his hall, sans hammer and protective belt. Loki promises to produce him, in exchange for his freedom.
Back in Asgard, Loki impresses Thor with his description of Geirrod's wonderful kingdom and hall.
From Loki's description, Geirrod's place seems to Thor like the ultimate vacation destination and party hot-spot, and he quickly agrees with Loki that they should make a visit there.
Loki casually suggests that Thor leave behind his hammer and belt, because no peaceful guest arrives fully armed. Thor agrees.
On the first night of their journey, Loki and Thor spend the night in the home of the giantess Grid.
Grid warns Thor that Geirrod is a tricky son-of-a-gun. She loans him her iron glove, protective belt, and staff, just in case.
The next day, Thor and Loki have to ford the river Vímur.
Thor braces himself with Grid's staff.
Loki holds onto Grid's belt, now tied around Thor's waist.
Upstream from them, one of Geirrod's daughters, Gjálp, straddles the river and begins to pee. If you think that's gross, hold on, because it gets better:
Gjálp pees so much that her urine stream creates massive waves. Thor and Loki are drowning in pee!
When Thor realizes that Gjálp is the cause of the trouble, he tells Loki that "you've got to stem a river at its source." He throws a rock at Gjálp. Then he grabs the branch of a rowan tree and pulls himself and Loki out of the river.
Thor searches for the nearest shower. (Okay, not really, but that's what we would do.)
Thor and Loki finally arrive at the home of Geirrod, who promptly leads them to (drumroll, please) the goat barn. Great hospitality, right?
Thor takes the only seat in the place. Much to his surprise, the seat starts to float, rising toward the ceiling.
The ceiling is getting way too close for comfort to Thor's head, so he pushes against it with Grid's staff and sends the chair flying back down to the ground.
He hears screams. Turns out Geirrod's daughters were underneath the chair, lifting it on their backs. They've been crushed to a bloody pulp.
This family is apparently not a close one, because Geirrod doesn't seem at all concerned that his daughters have just died a gruesome death. In fact, he invites Thor to play games.
Geirrod leads Thor to a hall with fires down its whole length.
The game is pretty simple: Geirrod uses tongs to throw a molten iron at Thor. (Ever seen that Friends episode where Joey and Chandler play fireball? Yeah. It's kind of like that.)
What Geirrod doesn't know is that Thor's got Grid's iron glove. He catches the molten iron, no problem.
And then he throws it back at Geirrod—right through his stomach.
Geirrod dies. Painfully.
Thor ends this story the way he usually does, by killing all the giants.