Mark of Cain

Working for the police had criminal psychologist Christian Moll losing so much sleep that, despite years of successfully helping investigators unwind the twisted minds of murderers, he decided to call it quits. But when a disturbing pattern in recent cases begins to emerge, he chooses to postpone his self-imposed retirement in order to help out an old flame.

Detective Katharina Rosenberg has a new case and a new cop killer on the run. When two colleagues are murdered in rapid succession, a shocking theory emerges: Is someone killing off the detectives Christian worked alongside solving homicide cases? And is Katharina next?

Now, Katharina and Christian must team up once again to catch the murderer before it's too late. With their buried passion rising to the surface, they give in to their desire while racing against time to find the vengeful cop killer before he finds them.