After a period of rehabilitation, Martin Beck is back on duty. He and the rest of the group are thrown into a case where the body of a notorious Danish professional criminal is found in the water at Liljeholmen. A body is found floating in the water near Liljeholmen. The dead man is a 39-year-old Danish citizen with a hefty criminal record as a member of a notorious Danish drug network. When his car is found in a suspicious location, Alex and Josef start running surveillance on it. It isn't long before one of the Danish man's associates shows up there. The Danish gang has been weakened over the course of several years after a big bust which sent many of their top ranked members to prison. Maybe the Swedes are preparing to take over? Is the Beck group about to get caught in the middle of a gang war? The gang's leader is serving time in Swedish prison, and the only person he is willing to talk to is Steinar Hovland.