Worlds collide when a powerful ancient enemy threatens to plunge the cosmos into eternal darkness. Thor fights to restore order across the cosmos, but an ancient race led by the vengeful Malekith returns to plunge the universe back into darkness. Faced with an enemy that even Odin and Asgard cannot withstand, Thor must embark on his most perilous and personal journey yet. Now, reunited with Jane Foster, and forced to forge an alliance with his treacherous brother Loki, Thor embarks on a perilous personal quest to save both Earth and Asgard from destruction.