Detective Carl Morck's 'Department Q' in Copenhagen, Denmark - which investigates cold cases - has a new task. Two boarding school students, a brother and sister, were killed twenty years ago and a clique of unruly fellow students were suspects. Evidence was lacking, however, and the students weren't charged. Then, almost a decade later, one of the students confessed and went to prison. The others went on their way, the men becoming rich, successful businessmen and the lone woman in the group becoming a homeless bag lady. Morck believes the whole clique committed the murders and decides to re-investigate the case.
The delinquent boarding school students are psychopaths who delight in beating up and killing people among other things. Their activities continue into adulthood and Morck's team uncovers a series of crimes the clique may have committed. The men in the group feel invulnerable because they have connections in high places and, in fact, certain police officials and politicians attempt to thwart Morck's investigation. Nevertheless the criminals are concerned. They know Kimmie (the bag lady) has a box of trophies from their victims and they're desperate to get the box. Thus Kimmie is being sought by thugs as well as the police. The lifestyles, debauchery, and criminal inclinations of Kimmie and the men are described in some detail and it's clear that the men are evil and Kimmie is deranged.
On the lighter side, Department Q - which started out with Morck and his very clever assistant Assad - is deemed to merit a new employee, secretary Rose Knudsen. Rose is a smart, strong-willed woman who's determined to enhance the basement facilities of Morck's squad. Morck doesn't like Rose though and - in his curmudgeonly fashion - plots to get rid of her. The interactions between Morck and Rose provide some of the more amusing moments in this very dark story.
Morck's team works hard to overcome obstacles and collect clues. Meanwhile, Morck is dealing with his personal issues, which include lusting after the department psychologist, worrying about his paralyzed former partner Hardy, and living with his teenage stepson.
The book is well-written, interesting, and comes to a satisfactory conclusion. However I didn't enjoy it as much as the first book in the Department Q series (The Keeper of Lost Causes) - which seems more balanced in terms of evil people/horrible crimes vs. amusing characters/scenes. Nevertheless, this is a good book, recommended for mystery fans.