It was supposed to look like journalist Harald Strauss died in an accident. But when Lena Odenthal and Mario Kopper start investigating, it quickly turns out that he was already dead when his car went off the road. Harald Strauss was poisoned. The journalist researched a pharmaceutical company that was developing a new weight-loss drug, a veritable "fat killer". But everything is fine with the drug, the pharmacologists responsible for the development, Dr. Kiel and Dr. Neumann. Kristina, Harald Strauss' ex-girlfriend, allegedly knows nothing. But Lena notices that the beautiful young woman who wants to make a career as a model has unusual eating habits and takes mysterious pills.
Kristina's ambition is to get even thinner than she already is. At the same time, her mood swings are so severe that Lena begins to worry about the young woman. When she discovers that Kristina took part in a series of tests for the fat killer "Nofamax", Lena suspects that Kristina's fear of persecution has something to do with it. Is there real danger for Kristina because she knows a little more about the drug than she's letting on, or is she just imagining the persecution?