Plot

A student stabs a woman and then kills himself. Katrin and Melly find that the persons did not know each other. On the boy's phone they find the message, 'Do it!', sent by his teacher Felix. There are parallels to another recent suicide.

Detectives Katrin König and Melly Böwe are dealing with a dramatic crime in Rostock. Two people die in the street. A young man stabs a woman and then kills himself. At the crime scene, König and Böwe are faced with a mystery: there is no discernible connection between Leon Schilling and his manager, Mona Färber. The only clue is a message on Schilling's cell phone: "Do it!" The message was sent by Felix Lange, a 28-year-old teacher, the night before the crime. However, Lange denies any involvement in the crime and claims to have known nothing of Schilling's intentions. But this is not the first time he has testified in a similar context: Felix had contact with Lara Trensbach, a 19-year-old woman who also recently took her own life in Rostock.