A holiday home on the river is set on fire and destroyed. A politician is also murdered. Fichte, Luise Bohn and Krüger are looking for arsonists and perpetrators in different ways. They come across the patient Maja Wiechmann in a psychiatric clinic. She has a dissociative identity disorder, and surprisingly, both cases come together. A mysterious woman appears at Krüger's construction vehicle and warns him of a danger. On the same day, the body of Gernwart Voss, local politician of the Oberspreewald-Lausitz district, is found, who was responsible for distributing structural change funds. In the face of this crime, Krüger Luise Bohn and Fichte provide information about his mysterious one „ Warnerin ".
Luise and Fichte, however, follow the trail of a arsonist who lit a holiday home near the body. Krüger recognizes the mysterious visitor in Maja Wiechmann. He deals with the psyche of Maja, who according to her empathetic supervisor, psychologist Jenny Trumaschek, is divided into six different personalities. But now a 7th seems to be in the disturbed Maja. To have made person wide. Who is this 7. Person? When Fichte and Luise finally end up in the psychiatric clinic during their investigation into the Voss murder case, the 7th. Person for an unexpected turn and to clarify the two cases and their relationships.