Top lawyer Corinne Perrault knows no mercy when her clients' interests are at stake. One morning she floats dead in Lake Zurich. What appears to be a suicide turns out to be an insidious murder. As a lawyer for the law firm Clement and Widmer, she represented the up-and-coming pharmaceutical company Argon. Allegedly, their drug Volmelia caused devastating damage during the test phase - for example with Klara Canetti. The girl is in a wheelchair because of a rare disease. After taking Volmelia, Klara's condition has now worsened. Now her mother has sued Argon. There is a lot at stake for the group, because the outrageously expensive drug is about to be approved. In the event of a ban, the company with its shooting star Dr. Regula Arnold misses many millions, which makes the pharmaceutical woman the main suspect in the murder of Corinne Perrault, especially in the eyes of Tessa. Perrault's death causes dismay in the firm. The noble company loses a qualified colleague. For lawyer Matteo Riva, Corinne was more than that, and boss Martina Widmer also had a lot in common with the dead. But Isabelle and Tessa do not trust the demonstrative dismay of the two. Then the commissioners find out that Corinne had given up the Volmelia mandate and was on sick leave for a longer period of time. The investigators are still pursuing a third lead - mainly at the instigation of Isabell. In her eyes, Klara's mother Dorit has a double motive for murder. The hatred of Corinne Perrault, who aggressively attacked her daughter in a survey, as well as the prospect of high financial compensation. Isabelle tries to gain Klara's trust. Then Klara collapses while being questioned by her and has to be put into an artificial coma. Isabelle blames herself because she feels guilty about Klara's condition. In addition, the girl is missing an important witness who could shed light on the death of Corinne Perrault.
—ARD Das Erste