Arne Dahl's A Unit has been disbanded for the last two years. When a wave of brutal murders hits Polish nurses in Sweden, the National Police see their chance to instate the unit again. Kerstin Holm, previously a member of the A Unit, is assigned to lead them. The A Units official role in the police force is to investigate complex, violent crimes with international connections. Kerstin builds her team with former members of the unit Nyberg, Chavez, Svenhagen and So derstedt, but she is assigned a new recruit as well, somewhat reluctantly - Ida Jankowicz, a wiry, yet powerful, rookie with exceptional language skills. Paul Hjelm, previously a key figure in the A Unit, has been promoted to a job as head of Internal Affairs. At first, he and the A Unit are pretty far removed from each other, but their paths will cross sooner than any of them could imagine. We meet a chastened unit of individuals who have allowed the all consuming nature of their police work to eat away at their private lives. Demands and expectations have never been higher and a cold wind blows through the corridors at the National Police headquarters. Can Kerstin get the unit to deliver or is this new effort a misguided attempt by a paranoid police force in a time of increasingly unusual and refined criminal activity?