Archaeologist Nina Wilde and her husband, Eddie Chase, are sent to recover a Viking runestone that has been stolen by a gang of raiders. The stone holds the key to an ancient evil that cannot be allowed to escape - one that has been confined in Norse mythology's most holy of places: Valhalla.
Eddie and Nina find themselves in a race against time to locate the legendary hall of the Viking warriors before rival powers claim its deadly contents for themselves. Their quest leads them to Scandinavia, where Eddie is forced to revisit a dark chapter from his days as a mercenary that he has kept hidden from everyone... even his wife.
A primordial terror is about to be unleashed from the depths of the Earth and the best chance of surviving its threat lies with Nina and Eddie. But even if they succeed, will the cost to their lives be worth the price they must pay?