On the night of his high school graduation, nineteen-year-old Milo Bohr expected a night out on the town, flashing fake IDs and ending up somewhere he couldn't remember. The last thing he expected to happen was his best friend transforming into a horned blue-skinned giant, screaming about Warriors of Thunder and someone called Odin. When the night comes to a screeching halt, with Milo waking up in a never-ending tower its Viking-like inhabitants call Valhalla, he realizes death came sooner than he thought.

A civil war rages across worlds, where a golden kingdom sits between mountains. The One-Eyed King Odin has fallen, and his son, the heir to the throne, is missing. Astrid, a belligerent warrior once a Royal Guard member sits in chains within the city's underground prison. As her fate takes an unexpected turn, Astrid escapes the war-torn realm with a terrifying mission: find the missing prince and restore Asgard to glory.

Four undead teens, brought together through death and the mysterious title 'Warriors of Thunder' find themselves under the power of a prophecy, with only the guidance of the reluctant Astrid to lead them through the world's Nine Realms. Can the Valhallians prevent Asgard's fighting gods from starting a world-ending battle before it's too late?