Thor has chosen to stay on Earth to help those in need, creating tension with Odin and leaving Asgard vulnerable. Frost Giants attack Earth, but Thor defeats them with Jane Foster's help. Meanwhile, Malekith, the Dark Elf sorcerer, steals the Casket of Ancient Winters from a hidden tomb and plans to use it and the Aether to conquer the nine realms. Thor, Jane, and Heimdall return to Asgard, where they discover the theft and Malekith's plot. As Malekith's forces invade Asgard, Thor is sent to Jotunheim, but manages to return and free his allies. Odin criticizes Thor for leaving Asgard unprotected, but Jane defends him, leading to a plan to stop Malekith.Thor assembles a team including Loki to track down Malekith. They journey to Svartalfheim, where Malekith bonds with the Aether, revealing it as an Infinity Stone. Despite initial setbacks and Loki's apparent betrayal, Thor and his allies engage Malekith and his forces in a final battle on Earth during the convergence of the nine realms. With help from Odin, Loki, and the Asgardian warriors, they manage to defeat Malekith and contain the Aether. Loki sacrifices himself to save the realms, earning honor and a statue in Asgard. Thor chooses to protect the nine realms while continuing his life on Earth with Jane.
