The nine-year-old Nikolas has been missing for days. The criminal psychologist Claudia Meinert notices contradictions in her conversation with his parents. 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 thirteen-year-old Leon and Mathilda strike the psychologist as conspicuous and provocative. Shortly afterwards, Meinert encounters the children with Nikolas' parents in the swimming baths, and her suspicions are confirmed... What happened with Nikolas?