A turbulent 24 hours begin for the Weimar detectives Kira Dorn and Lessing when the three-time woman murderer Gotthilf Bigamiluschvatokovtschvili, known as Gobi, breaks out of the forensic psychiatric ward five years after his conviction. He leaves behind a strangled nurse and her young colleague who is in shock. That same night, the wife of Professor Eisler, head of psychiatry, is found dead in her own bed. Gobi seems to be on a vendetta. On the hunt for the desert Gobi, the inspectors not only come across his preferences for women and homemade underwear. The investigation also leads Kira Dorn and Lessing to his jealous fiancée Mimi Kalkbrenner, a full- time harpist who may have helped Gobi escape.
As evidence gradually emerges that calls Gobi's perpetrators into question, Professor Eisler, who has had a questionable relationship with his ailing wife in recent years, becomes the focus of the investigations. Are the recent murders a "freeboard strangle"? A missing earlier investigation file and the secretive former head of the police department, Bruno Götze, who arrested Gobi five years ago, make solving the murders more difficult. The hunt for the culprit also leads Dorn and Lessing into the sewers of the city of Weimar, which is as murky as the web of entanglements that the inspectors get caught up in.