In their sixth joint case, the Berlin "Tatort" investigators Nina Rubin (Meret Becker) and Robert Karow (Mark Waschke) are called to the outskirts. A body was found in a burned-out van. Rubin and Karow quickly determine that there were three other, older cases with a similar course of events. They were never enlightened. Is it a serial killer? Another link leads to Berlin-Wannsee: all victims were conceived with the help of in-vitro fertilization in a fertility clinic. Managing Director Dr. Irene Wohlleben (Almut Zilcher) and her laboratory manager and life partner Hanneke Tietzsche (Eleonore Weisgerber) recently handed over the management of the clinic to Irene's son Dr. Handed over to Stefan Wohlleben (Trystan Pütter). He was born in the 1980s as one of the first test tube babies in Germany.
During their investigations, the inspectors also come across a loner named Harbinger (Christoph Bach). As a 16-year-old he attacked Irene Wohlleben, today he runs a key service in a Berlin subway station. Harbinger used to be called Werner Lothar and, according to his psychiatrist, suffers from borderline syndrome. Robert Karow uses unusual methods to try to gain the eccentric man's trust and lure him out of his reserve. Anna Feil (Carolyn Genzkow), now a candidate for the detective, makes an unbelievable discovery on her own behalf in this case. And on the fringes of the investigation, Nina Rubin has a serious argument with her older son Tolya (Jonas Hämmerle). In addition to the commissioners, Berlin again takes on the third leading role.
This time the perspective changes: The film shows Berlin's underworld under Alexanderplatz and under Steglitzer Schlossstrasse and also leads to places such as an iron foundry in Wilhelmsruh, which was available for filming for the first time.