Two years after the Battle of Sokovia,[N 1] Thor has been unsuccessfully searching for the Infinity Stones, and is now imprisoned by the fire demon Surtur. Surtur reveals that Thor’s father Odin is no longer on Asgard, and that the realm will soon be destroyed in the prophesied Ragnarök, once Surtur unites his crown with the Eternal Flame that burns beneath the city. Thor defeats Surtur and claims his crown, believing he has prevented Ragnarök.
Thor returns to Asgard to find his adopted brother Loki posing as Odin. Thor forces Loki to help him find their father, and with directions from Stephen Strange on Earth, they locate Odin in Norway. Odin explains that he is dying, and that his passing will allow his firstborn child, Hela, to escape from a prison she was sealed in long ago. Hela had been the leader of Asgard’s armies, and had conquered the Nine Realms with Odin, but had been imprisoned and written out of history after her ambitions became too great. Odin dies, and Hela appears. She destroys Thor’s hammer Mjolnir, and when Thor and Loki attempt to flee through the Bifröst Bridge, she pursues them and forces them out into space to die. Hela arrives in Asgard, destroying its army and the Warriors Three; resurrects the ancient dead who once fought with her, including her giant wolf Fenris; and appoints the Asgardian Skurge as her executioner. She plans to use the Bifröst to expand Asgard’s empire, but Heimdall covertly steals the sword that controls the Bridge, and hides away with the rest of Asgard’s citizens.