In a detached house in Munich, inspectors Batic and Leitmayr find the bodies of Michaela Danzer and Daniel Ruppert, who has been fatally shot. The dead man's six-year-old son has disappeared and is found completely distraught in front of a hospital on the night of the crime. The boy is apparently an important witness, but he doesn't say a word. Did he see the culprit? Before the inspectors get an answer to this question, Quirin disappears from the clinic. The suspicion of having kidnapped him initially falls on his biological father. During emergency surgery on surviving victim Daniel Ruppert, doctors discover the scar from an old gunshot wound. The scar leads Batic and Leitmayr to the trail of a crime that killed almost an entire family in Augsburg 15 years ago.
What happened there seems to have been tragically repeated today. At that time there was one survivor: Ella, the seven-year-old daughter of Daniel Ruppert. The fact that the perpetrator from back then is the victim of today causes Batic and Leitmayr some headaches, especially since Ella's trail is lost in the void a few years after the tragedy in Augsburg. Did she take revenge on her father 15 years later ? Or is the crime an act of jealousy by the dead man's estranged husband, who is fighting for custody of Quirin? The search for Ella leads the investigators to the Munich Zoo, where she works as an animal keeper for the elephants. It looks as if Ella has the boy with her, but she has disappeared from the working container, where she was apparently hiding with him.
The trainer Lissy, who knows Ella from her self-defense courses, doesn't help the investigators either. What does the young woman, who is still struggling with the trauma of her childhood, have in mind for Quirin? Case analyst Christine Lerch fears that Ella will slip further and further into her old trauma while she is withdrawn from the pills and will no longer be able to distinguish between today and yesterday. What danger is the boy facing? When Batic and Leitmayr finally find out through Lissy where they are, all they see is an empty rowing boat on the lake. Quirin's stuffed elephant bobbles in the water at the jetty. Did Ella pursue revenge after her father survived? Or is she not the culprit at all? who shot Where's the fault? And can Ella and Quirin's lives be saved?