The Thor Dark World

Eons ago, Bor, the father of Odin, clashes with the Dark Elf Malekith, who seeks to destroy the universe using a weapon known as the Aether. After conquering Malekith's forces, including enhanced warriors called the Kursed, on their home world of Svartalfheim, Bor safeguards the Aether within a stone column. Unbeknownst to Bor, Malekith, his lieutenant Algrim, and a handful of Dark Elves escape into suspended animation.

In present-day Asgard, Loki stands imprisoned for his war crimes on Earth. Meanwhile, Thor, alongside warriors Fandral, Volstagg and Sif, repels marauders on Vanaheim, home of their comrade Hogun; it is the final battle in a war to pacify the Nine Realms following the reconstruction of Bifröst, the "Rainbow Bridge" between realms, which had been destroyed two years earlier. The Asgardians soon learn that the Convergence, a rare alignment of the Nine Realms, is imminent; as the event approaches, portals linking the worlds appear at random.

In London, astrophysicist Dr. Jane Foster and her intern Darcy Lewis travel to an abandoned factory where such portals have appeared, disrupting the laws of physics around them. Separating from the group, Jane is teleported to another world, where she is infected by the Aether. Heimdall alerts Thor that Jane has moved beyond his near omnipotent sight, leading Thor to Earth. When Thor finds Jane, she inadvertently releases an unearthly force, and Thor returns with her to Asgard. Odin, recognizing the Aether, warns that the Aether will not only kill Jane, but that its return heralds a catastrophic prophecy.

Malekith, awakened by the Aether's release, turns Algrim into a Kursed and attacks Asgard. During the battle, Malekith and Algrim search for Jane, sensing that she contains the Aether. Thor's mother Frigga is killed protecting Jane, and Malekith and Algrim are forced to flee without Jane. Despite Odin's orders not to leave Asgard, Thor reluctantly enlists the help of Loki, who knows of a secret portal to Svartalfheim, where they will use Jane to lure and confront Malekith, away from Asgard. In return, Thor promises Loki vengeance on Malekith for killing their mother. With Volstagg and Sif stalling Asgardian soldiers and Fandral assisting their escape, Thor, Loki, and Jane bolt to Svartalfheim.