Sauerland, autumn 1995: In the middle of the forest on the Wilzenberg, a walker finds the body of high school graduate Sonja Risse. However, the fact that the killer left a music box with the lullaby "Hush Little Baby" at the crime scene does not lead to a clear solving. 25 years later, the investigative journalist Stefanie Schneider, known as "Mütze", made a surprising discovery in Cologne. In a disused multi-storey car park, she films an undressed corpse of a man with a music box running next ...