Markus Möller, owner of an event agency, is murdered during a company party that his agency organized for an insurance company. In the course of their investigations, Lena Odenthal and Mario Kopper come across unclean processes in the company. They wonder whether Möller's brother Jörg or his colleague and ex-lover Martina knew about the fraudulent intentions and therefore Möller had to die. But Rike Hoffmann also seems suspicious. The young insurance clerk wasthe last Markus Möller was seen with. She is extremely scared and nervous. Lena Odenthal finds out that Rike had been the victim of a stalker for some time, who seemed to know her every move and harassed her with calls and gifts. Is there a connection between the two cases? Was Markus Möller the unknown? And did Rike Hoffmann decide to fight him that evening?