Loki learns that he & Thor have a half-sister named Hela whom Odin imprisoned many years ago. He releases her and they work together to get revenge on Odin by destroying everything about him, starting with manipulating the giant lords Ymir & Surtur into fighting each other in a battle that can destroy Asgard, igniting Ragnarok. Thor must make new allies to stop his two evil siblings. Along the way, Thor meets a long lost member of his family.
