Thor: The Dark World (2013) follows Thor as he battles Malekith, the leader of the Dark Elves, who seeks to plunge the universe into darkness using the Aether, a powerful ancient force.
After the convergence of the Nine Realms begins, Jane Foster accidentally absorbs the Aether, making her a target for Malekith. Thor takes her to Asgard for protection, but Malekith attacks, leading to the tragic death of Thor’s mother, Frigga. Seeking revenge, Thor frees Loki and forms an uneasy alliance with him.
Thor and Loki travel to Svartalfheim, where Loki fakes his death while helping Thor confront Malekith. Despite Thor’s efforts, Malekith escapes to Earth to unleash the Aether’s power during the convergence.
In the climactic battle in London, Thor fights Malekith across different realms while relying on Jane and her team’s scientific knowledge. Using their technology, they disrupt the Aether’s energy, allowing Thor to defeat Malekith and send him back to his realm.
With the Aether secured, Thor declines Odin’s throne, choosing to protect the realms as a warrior. Meanwhile, Loki, revealed to be alive, secretly takes Odin’s place on the throne, setting up future conflicts in the MCU.