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.

Maggie (Karoline Schuch) was right: Kai (Julius Gause) is alive! The siblings hide together in the abandoned forest hut. Kai's confession that he has many people on his conscience upsets Maggie just as much as his seemingly unimaginable explanation. After an attempted assassination, they are both in constant danger. Maggie turns to Voit (Felix Kramer) - without telling him that her brother is alive or revealing anything about his involvement in the series of crimes. Meanwhile, Voit's colleague Zajak (Lucas Gregorowicz) deciphers a mysterious document left behind by the survivor of the pile of corpses before his death. On the Polish side, schoolgirl Ilona (Nicola Magdalena Lüders) makes an eerie discovery. Something is wrong at the secluded boarding school for street children and runaways. Blood donations are compulsory, girls are disappearing and sinister men are coming and going.