Thor (2011)

In 970 A.D., Odin, king of Asgard, wages war against the Frost Giants of Jotunheim and their leader Laufey, to prevent them conquering the Nine Realms, starting with Midgard (Earth). The Asgardian warriors defeat the Frost Giant's and seize the source of their power, the Casket of Ancient Winters. In the present, Odin's son Thor prepares to ascend to the throne of Asgard as King but is interrupted when the Frost Giants attempt to retrieve the Casket. Against Odin's order, Thor travels to Jotunheim to confront Laufey, accompanied by his brother Loki, childhood friendSif and the Warriors Three: Volstagg, Fandral, and Hogun. A battle ensues which forces Odin to intervene and save their lives, destroying the fragile truce between the two races. For his arrogance, Odin strips Thor of his godly power and exiles him to Earth, accompanied by his Hammer - and source of his power - Mjølner, now protected by a spell to allow only the worthy to wield it.

Thor arrives in New Mexico and is found by scientist Jane Foster, her assistant Darcy Lewis and mentor Dr. Erik Selvig while Mjølner is discovered by agent Phil Coulson and confiscated by S.H.I.E.L.D. Coulson forcibly acquires Jane's data about the wormhole that delivered Thor to Earth. Thor, having discovered the location of Mjølner, attacks the S.H.I.E.L.D facility to retrieve it, only to find himself unable to lift it, and is captured by S.H.I.E.L.D. He is eventually freed and resigns himself to exile on Earth as he develops a romance with Jane.

Meanwhile, Loki discovers that he is Laufey's son and was adopted by Odin after the war ended. When Odin, overcome with stress, falls into the Odinsleep, Loki is given the throne as Regent and offers Laufey the chance to kill Odin as well as retrieve the Casket. Sif and the Warriors Three, unhappy with Loki's rule, attempt to discover a way to end Thor's exile, convincing Heimdall, gatekeeper of the Bifrost Bridge - the means of traveling between worlds - to allow them passage to Earth. Aware of their plan, Loki sends The Destroyer, a seemingly-invincible, metallic Golem, to pursue them and kill Thor. Sif and the Warriors Three find Thor but are attacked and defeated by the Destroyer, forcing Thor to sacrifice himself to save them and Jane. In doing so, he proves worthy to wield Mjølner, and the hammer returns to him, restoring his powers and allowing him to defeat the Destroyer before he prepares to return to Asgard and confront Loki.

In Asgard, Loki betrays and kills Laufey, revealing his true plan to use their attempt on Odin's life as an excuse to destroy Jotunheim with the Bifrost Bridge and prove himself worthy to Odin. Thor arrives and fights his brother before destroying the Bifrost Bridge to stop his plan, stranding himself in Asgard. Odin awakens and prevents the brothers from falling into the abyss created in the wake of the Bifrost Bridge's destruction, but Loki, believing he has failed Odin, allows himself to fall to his apparent death. Thor makes amends with Odin, admitting he is not ready to be King, while on Earth Jane and her team search for a way to open a portal to Asgard so that Jane can reunite with Thor.

In a post-credits scene, Dr. Selvig is taken to a S.H.I.E.L.D. facility where he meets Nick Fury. Fury asks Selvig to study the recently-discovered Cosmic Cube, which holds untold power, to which Selvig agrees. It is then revealed that Selvig is under the control of Loki who remains invisible yet manipulative of the weaker minded humans he now lives among after having been transported to Earth.