Two years after the battle of Sokovia,[a] Thor is imprisoned by the fire demon Surtur, who reveals that Thor's father Odin is no longer on Asgard. He explains that the realm will soon be destroyed during the prophesied apocalypse Ragnark, once Surtur unites his crown with the Eternal Flame that burns in Odin's vault. Thor frees himself, defeats Surtur, and takes his crown, believing he has prevented Ragnark. Thor returns to Asgard to find Heimdall gone and his estranged brother Loki posing as Odin. He forces Loki to help find their father, who Loki put a spell on after his presumed sacrifice years before.