Nina Moretti's 9th case: Ne bis in idem. Never twice for the same act. The legal principle, which was already applied in Roman times and is also enshrined in the German Basic Law, puts Chief Inspector Nina Moretti to a tough test of patience. Almost exactly ten years ago, the body of a young woman was found in the Westerwald. The suspected perpetrator was quickly apprehended at that time. However, the judge doubted the defendant's guilt and acquitted him. Now, another murder occurs. At the same location and under the same circumstances. But is it also the same perpetrator? For retired Chief Inspector Hans Peter Thiel, who led the investigation back then, the case seems clear. But the tables turn, and the hunter becomes the hunted. Thiel himself comes under investigation. Nina Moretti is faced with a puzzle. Is the former colleague truly capable of such a crime?.