The movie starts on Earth with Jane Foster watching some anomalies in the sky. Things get crazy, so she and her colleagues Darcy (Kat Dennings) and Selvig (old Norwegian guy) get in their cat to leave and run over Thor. She says "Where did he come from" and it goes to a voice over from Heimdall, which introduces Asgard.
Asgard starts with Thor about to be crowned king by Odin, who is close to going into the Odinsleep. The ceremony is interrupted by Frost Giants trying to steal an artifact, but they are killed by the Destroyer (who seems to do whatever the king wishes, but is not controlled by a host like the comics).
Thor is pissed at the attempted theft and wants to attack the Frost Giants. Odin says no, but Loki eggs him on. So Thor, Sif, Loki and the Warriors Three head to Jutenheim to kick ass. Things go to hell and Odin comes saves them. He is pissed at Thor and they get into an argument, then he takes Thor's powers and hammer and sends him to Earth.
Cut to Thor getting hit by the car. He wakes up and is all confused and acts like a dick and seems crazy, so he gets Tasered by Darcy. Then they take him to a hospital. He wakes up there and eventually they come back for him (I won't get into it all). He is very arrogant and no one likes him. Meanwhile Mjolnir has landed on Earth (Odin threw it after Thor after reciting the "whoever lifts this hammer.... if he be worthy" line) and when Thor hears about it, he wants to get it. The locals have been having contests to lift it (no one can), but the site is now taken over by SHIELD. Thor breaks in and beats up all the SHIELD guys, then goes to the hammer, but can't lift it. Clint Barton is in this scene as a sharpshooter about to take out Thor (who is mortal), but doesn't do it because Thor gives himself up to the agents, all dejected.
Meanwhile on Asgard, Odin tells Loki that he was actually a frost giant that Odin found after a big battle and adopted. Loki gets all upset, but then Odin collapses into the Odinsleep. Loki is next in line, so he takes over. The Warriors Three figure out that it was Loki who let the Frost Giants in to Asgard, but he has Odin's staff and power now, so they can't do anything and decide to head to Earth to find Thor. Loki cuts a deal with the king of the Frost Giants (his real father) to divide up the 9 realms. He then visits Thor in the SHIELD holding facility and tells him that Odin died and he can't reverse the banishment. Thor buys it and is all dejected.
On Earth, Jane and crew get SHIELD to release Thor, claiming that he is their colleague Dr. Donald Blake (the name of Jane's ex-boyfriend, not shown in the movie). This works, but only because SHIELD wants to follow them. They just hang out for a while and Thor is all humble and nice now. He and Jane start to fall in love.
Loki sends the Destroyer to Earth to kill Thor, but first kills some SHIELD guys like in the comic con footage. The Warriors Three and Sif (who found him) try to fight, but get their butts kicked. Thor tries to fight it, but is human so he gets near killed with one punch. The destroyer is about to finish him off when the hammer comes flying to Thor and he is a god again (also cut to a scene with Odin's eye shedding a single tear while sleeping). Thor has his armor and cape again and destroys the destroyer. The script has him flying in this scene. Then Thor, Sif and the Three head to Asgard.
Meanwhile, Loki lets the Frost King in to kill the sleeping Odin, but then double crosses him and kills him (Frost king) instead. He's all proud of himself now, but Thor shows up and they fight. Loki tries to blow up Jotenheim with energy of the rainbow bridge, but Thor stops him by breaking the Rainbow Bridge. Odin (now awake) shows up to save the two brothers from falling off the bridge, but Loki lets go and falls into oblivion (until the sequel).
The movie ends with Thor stuck in Asgard, but longing for Jane Foster.
I've left out a lot, but here are the cool parts:
- the rainbow bridge
- Thor flies
- Powerless Thor in custody and being visited by Loki in "modern clothes", kind of like Ultimate Thor
- Dr. Pym gets a mention
- Hawkeye is a SHIELD sniper (with a rifle)
- Sif and the Warriors Three are straight out of the comic
- Odin rides an 8 legged horse, like the comic
- Heimdall is awesome
- Frost Giants seem to be done well
- Human Thor is done well
- the Don Blake reference is good
- script mentions Stan Lee cameo