The nine-year-old Nikolas has been missing for days. The criminal psychologist Claudia Meinert notices contradictions in her conversation with the parents of the missing child. In particular Nikolas' mother appears to be hiding something. When a video of the missing Nikolas surfaces, showing him tied up in a cellar, the trail leads to his school. The 13-year-old Leon and Mathilda strike the psychologist as conspicuous and provocative. Shortly afterwards, Meinert encounters the children with Nikolas' parents at the local swimming pool and her suspicions are confirmed: the parents are entangled in an insidious father-mother-child game with the possible suspects Leon and Mathilda. Now it is up to the psychologist to resolve the dark mystery of Nikolas' disappearance and save the child.