Five-year-old Anne Sachs was playing with her Treperenda doll in her room when she heard a scream from the next room. Someone had hurt her mother. Unbeknownst to the girl, she had become a witness to a murder. Detective Steve Carella is on the trail of the perpetrator, but at a crucial moment he falls into a trap. Mayer and his rebellious assistant Bert Kling take over the investigation. Both must explain Carella's disappearance and find out who killed Karin Sachs and why. Her ex-husband Denis, little Anne's father, is scrupulously keeping the couple's troubled past a secret.