Nine-year-old Nikolas has been missing for days. The criminal psychologist Claudia Meinert discovers contradictions in her dealings with the child’s parents. Particularly, Nikolas’ mother seems to be hiding something.

When a video surfaces showing the missing boy shackled in a basement, the evidence leads to his school. 13-year-old Leon and Mathilda behave oddly and provocative when questioned by the psychologist. When Meinert then finds them both with Nikolas’ parents at the local swimming pool, her suspicions are confirmed: the parents are involved in a perfidious father-mother-child game with the assumed perpetrators Leon and Mathilda.

Now it’s up to the psychologist to decipher the dark secret surrounding Nikolas’ disappearance and to save the boy.