Dodgy beat cop Arnold Wijffels, moonlighting as security for the Maastricht golf club, is shot there. Shortly after, two corpses, also shot, are dragged from the river. Although Wolfs has to deal with his daughter's relapse in rehab, he soon works out it's all about Turkish drug-trading street gangs, one of which operates from over the Belgian border. The part of wayward dropout youngster Ab de Groot, whom evidence situates on the cop murder spot, his roughing-up and his genealogy prove the key.