Asgard, long before the events of the Thor films. Thor is a teenager fighting staged arena matches with a sword, Loki is quietly learning magic from the Enchantress, and Sif is training toward the Valkyries while the Warriors Three spin tales taller than anything they have actually done. Stung by feeling untested, Thor takes Loki's bait about a legendary weapon hidden in Jotunheim and stows away aboard the Warriors Three's ship, a trip that detours through a tavern and ends in a wrecked barroom before the group commits to the journey for real. In the frozen wilds they find the Sword of Surtur, and a pursuit by frost giants forces Thor to use it, killing two of them and cracking the bridge between realms. The fallout is a full Jotun army at Asgard's gates. Back home, Algrim reveals himself as no ally at all, taking the sword and cutting down the A ...