In the underworld, Loki sets a plan in motion. Sigrid and Leif recruit a band of warriors and launch a quest for weapons made of god-killing iron.

Leif and Loki find themselves trapped in a cursed realm. A pack of First Wolves aids the warriors. Sigrid's story attracts surprising new allies.

The epic battle begins as mortals, giants and Vanir deities clash swords with Thor and his Aesir soldiers. A risky secret mission ends in bloodshed.