Tyr, God of War, elder brother of Thor, embarks on a quest to regain his honor and place at Odin's side. Spurred on by loyal young Bjorn Wolfbane and the bewitching Lorelai, the trio set out to steal a sliver of Twilight, sword of the fire giant Surtur, who will one day bring about Ragnarok and destroy Asgard. But the fiery realm of Muspelheim is fraught with volcanic trolls, lava kraken, and Surtur's brood of murderous warriors. Tyr must overcome his own feelings of inadequacy and the motives of his allies or risk triggering the apocalypse and cursing his name forever.