Elin Warner is on vacation with her brother Isaac in a rugged national park in Portugal—the last place Kier was seen. It’s supposed to be a time for the siblings to reconnect, but when Elin discovers Kier’s disturbing final map, it seems the park—especially the inhabitants of a camp buried deep in the forest—holds clues to what happened to Kier, and a lot more besides.
After a sinister discovery, Elin is shocked to learn Kier's disappearance is more personal to her than she’d ever imagined. And as she seeks the truth, Elin soon finds the wilderness hides something far darker than shifting shadows…