Heather and Phil travel to the most haunted chateau in France to investigate terrifying stories of hostile ghosts linked to strange and savage murders. As they investigate, it becomes clear that the castle hosts more paranormal forces than they imagined.

Heather and Phil continue their deep dive into Nazi occult activity in nearby Poland, where they investigate Nazi strongholds that harbor terrifying secrets. Their search suddenly leads them to a man-made network of tunnels hiding supernatural relics.