Two cars collide head-to-head on a country road with little traffic. The collision is violent. Ten year old Cecilia is catapulted through the windscreen and killed. Five years later, criminal detective Walter Grohn gets a perplexing case on his desk - one dead taxi driver and his killer who has no idea why he committed the crime. The first murder is followed by others, all equally as brutal and inexplicable. Together with his talented assistant, Jonna de Brugge, he untangles threads that lead back to the very core of the Swedish justice/judicial system.              

The mastermind behind several brutal murders seems to have disappeared from the face of the planet and the investigation is stalled. Detective Inspector Walter Gröhn searches in vain for clues when a hostage drama suddenly leads the hunt in an unexpected direction. Everything points to a kidnapping of the man responsible, but by whom? And for what reason? At the same time, suspicions arise about an infiltrator in the investigation. Someone inside the police headquarters seems to be doing their utmost to prevent the murderer being found. A special task force is assembled and once again, Walter and Jonna de Brugge are working side by side, against an adversary who always seems to be one step ahead.