A hill. An old mine. A secret. In the picturesque beauty of the Teutoburg Forest, specifically in Hagen a.T.W., the trail of Maike Wasmuth's former school friend goes cold. Together with her colleague Patrick Bonhof, the chief inspector begins her investigation and quickly reaches her limits. The elderly villagers behave strangely and tell odd stories. She learns that these tales are connected to a long-ago event. But which story of the old mine is not meant to be told? And what does that mean for the disappearance of her friend? Only the case analyst Roman Sellberg recognizes the eerie connection between the two events and can provide the crucial clue. They break through the wall of silence and discover the truth behind the Blood Hill...