Chris Harper, an attractive and popular teenage boy, was found murdered with his head bashed in on the grounds of St. Kilda's, the girls' boarding school near the boys' boarding school that Chris attended. An intensive investigation produced only one possible suspect and no real evidence and a year later, the case remains unsolved. Now, Holly Mackey, a sixteen-year-old student at St. Kilda's and the daughter of Detective Frank Mackey of the Dublin Murder Squad, appears at police headquarters with a photo of the dead boy. The caption on the photo claims, "I know who killed him."

Holly found the photo on the Secret Place, a bulletin board at the school where students are allowed to make anonymous postings. Rather than giving the photo to her father, Holly delivers it to Detective Stephen Moran who is on the Cold Case Squad. Holly had been a witness in an earlier case that Moran had handled and apparently feels more comfortable entrusting him with the information that could finally produce a solution to the case.

Moran is anxious to get out of the Cold Case unit and into Homicide, and he sees this as an opportunity to make the jump. He takes the photo to Detective Antoinette Conway, the primary on the Harper case and convinces Conway to let him tag along as she goes out to the school to reopen the investigation by attempting to determine who might have posted the photo on the Secret Place and what that person might really know.

Through the course of a very long day and night, Conway and Moran interview the staff and students at St. Kilda's and gradually suspicion focuses on two rival groups of students, one of which includes Holly Mackey. The girls have agendas of their own, and it's quickly apparent that none of them can be trusted as truthful.

Tana French clearly understands the world of these young girls--or at least it appears that she does--and the portrait that she paints makes me very glad of the fact that I am not and never was a teenage girl. The cat and mouse game between the young women and the detectives is a thing to behold and the relationship between the detectives themselves is very interesting and fraught with potential problems. And whether any solution to the murder will ever be forthcoming is very much in doubt.

French writes beautifully and, for me, that was the saving grace of this book. I've really enjoyed most of the other books in this series, but this one seemed to drag on longer than it should have--or at least longer than I wanted it to. It's a very dense 452 pages and the main problem for me was that I couldn't find a single character sympathetic enough to care about. 

The girls, Holly Mackey included, are mostly a bunch of conniving little snots and watching the way their friendships and rivalries played out was interesting for a while, but after about 300 pages, I'd had about enough of it. Each of the two detectives is emotionally damaged; neither of them has good social skills; they both have problems relating to other people, and I personally didn't care much about them either.

In her earlier novels, French has created a number of very interesting characters, both cops and victims that I really did care about, including Holly Mackey's father, Frank, who is a much more intriguing than any of the characters who populate this book. Sadly, that isn't the case here and thus three stars for me rather than four.