The body of 25-year-old paralegal Karin Berling (Stefanie von Poser) is recovered on the banks of the Danube in Regensburg. The parents are stunned, especially since their daughter Karin was about to marry the Turk Cengiz Özgür (Baki Davrak). The husband-to-be reacted to the news of his death with horror, but initial research made it clear that his relationship with Karin was about to end. One cause was the contentious relationship with his future parents-in-law, another, the close relationship between Karin and Klaus Webert. Klaus Webert (Tobias Oertel), who has no alibi for the time of the crime, comes under suspicion, but Cengiz's brother Mehmet (René Ifrah) is also among the suspects when it turns out that he is strongly committed to the fundamentalist movement.
Commissioner Lucas realizes that she can only solve the case if she also understands the religious and political ties behind itKnowing how to decipher events. Karin's superior, the well-known lawyer Tansu Nasiri (Idil Üner), gives her valuable background knowledge. In the middle of an interrogation, the unbelievable happens. The lawyer is shot in an ambush and only at the last minute does Inspector Lucas manage to save Nasiri's life. Now the assumption is obvious that a political motive is also possible in the case of Karin. The political explosiveness of the case reaches a new dimension when Attorney General Stahmer (Jan-Gregor Kremp) intervenes. The situation escalates when Cengiz's sister Leyla (Pegah Ferydoni), an important witness, suddenly disappears.
The worst must be feared, and the massive threats against the lawyer Nasiri don't stop, they even extend to Inspector Lucas. One thing is becoming increasingly clear to her: that the lawyer Nasiri seems to know more than she is letting on..