In the small town of Wäldern in the Bergisches Land, young people are mysteriously disappearing. It quickly becomes clear that these are not normal missing persons cases - an ancient danger lurks in a labyrinth beneath the town. Lara Glanz is still looking for her niece Magda, who the police have declared dead. but then Merle appears out of nowhere, standing dripping wet in her parents' garden. The girl is a different person - she speaks loving words, but moves through her former home as if remotely controlled. Above all, however, Merle seeks Lara's company. It turns out that Lara and her past are themselves part of the strange occurrences in Wäldern.