Shrouded: Book 6 (Thor's Dragon Rider)

A dishonorable death, hunted by criminals, and souls severed.
Asgard mourns a beloved god who should spend his afterlife in Valhalla but dies out of battle, trapping him in Helheim. Following orders from Odin and his wife, Frigg, Thor takes Kara and the combined Valkyrie and dragon entourage to the underworld in hopes of attaining his release.
Impossible demands must be fulfilled, and the threats the group face require the skills of every companion.
Will a soul be lost to save a soul?