The movie begins with the clash of Bor and Malekith, where Malekith wants to destroy the nine realms by unleashing a weapon known as Aether. But Bor conquers the forces of Malekith and stops him from unleashing the weapon. He protects the Aether with a stone column. Years later, Thor is trying to pacify the nine realms along with his Warriors. In London, Jane, who is an astrophysicist is teleported to another world where she gets affected by Aether.
When Thor gets to know about it, he decides to find Jane and bring her to Asgard to save her and the catastrophic consequences that may be encountered due to the Aether. When the Aether is released, Malekith awakens and he gets on the mission of finding Jane and taking the Aether from her. Thor along with Loki, battles with Malekith to not let him succeed in his evil intentions and also to protect Jane.