The large LKA contingent is searching for a serial killer in Krewlow and hopes to get a clue from the only survivor found on the pile of corpses. However, the seriously injured man is unresponsive. For the village doctor Frank Seeger (Torsten Ranft), it is clear that "Pulver-Paul" (André M. Hennicke) is behind the bloody deeds. The gun-crazy hermit is holed up on his farm and obsessively believes he has to defend himself against overpowering enemies. When Roland Voit (Felix Kramer) and Stanislaw Zajak (Lucas Gregorowicz) want to interrogate him, a life-threatening confrontation ensues. Meanwhile, Maggie (Karoline Schuch) is staying with Adrian Demko (Jan Krauter), her childhood friend who is in a wheelchair. She is convinced that the key to the Oderbruch serial murders lies in their shared past.

In a mysterious vault beneath the pile of corpses, the police units discover not only more bones, but also a jar of water with leeches. The seemingly insignificant find awakens the memory of Kai, Maggie's missing brother, in Roland Voit (Felix Kramer) and Maggie Kring (Karoline Schuch). Kai was an extraordinary, mysterious boy. Maggie simply cannot and will not believe that he is no longer alive and now hopes to have found proof of this. She asks Adrian Demko (Jan Krauter) for help. Adrian has been in a wheelchair since a terrible accident in their youth, when an unexploded bomb from the Second World War exploded. He instructs his carer Marek Gorski (Adrian Topol) to accompany Maggie on a trip across the border to Poland. The trail leads them to a mysterious building in the border area - where Maggie is assassinated.

Poland, summer 1990: ten-year-old Kai (Edgar Emil Garde) has been taken to safety by his mother Minna (Uta Janietz) to stay with Polish friends. His father Arthur (Stefan Weinert) wants to kill him because he suspects that Kai has a sinister tendency. His sister Maggie (Alix Heyblom) fearlessly stands up for Kai and has to protect him from other children. A fight breaks out on the way to school, in which the leader Conradi (Bennet Mai) is seriously injured and Maggie is knocked unconscious. Kai swears to his father that he will never tell Maggie the truth about himself. A sinister man (Liliom Lewald) also knows that the introverted boy is special. He seeks Kai out and offers him the chance to live with his "real" family.

Kai (Julius Gause) can't live with his guilt and wants to shoot himself. Maggie (Karoline Schuch) saves him at the last second. She wants to give her brother the chance to work together to find the people behind the unimaginable crimes and make amends. In order to stop the series of crimes, the ex-policewoman sets out in search of the key figure: the "Great Hunter". A trail leads back to 1947, when two men came under suspicion of having committed gruesome murders. One of the suspects was Maggie's now 90-year-old father Arthur (Volkmar Kleinert), the other disappeared a long time ago. Together with Roland (Felix Kramer), Maggie uncovers a disturbing family secret.