The Secret Place by Tana French

Detective Stephen Moran has been stuck in the Cold Case department in the Dublin police force for far longer than he'd like.  He wants to work in the Murder Squad, like most other policemen but he doesn't seem to be making any progress in getting noticed there.  That may change the day Holly Mackey brings him a card.

Stephen met Holly years before when she was a child and a witness to a crime.  Now she is sixteen and the card she brings him has the picture of a boy, Chris Harper, and the words, "I know who killed him" on it.  Chris Harper was a student at a boy's exclusive school.  His body was found on the grounds of the neighboring girl's school, St. Kilda, where Holly attends school.

Stephen knows that this case got nowhere last year when the murder occurred.  Maybe this is his chance to make a splash and get the transfer he wants.  He brings the card to the lead detective on the Harper murder, Annette Conway.  Known for her abrasive manner, she agrees to let Stephen accompany her to St. Kilda to see if they can discover who posted the card and who might know something about the murder they didn't tell last year.

Suspicion soon narrows down to two groups of girls, rival cliques in the school.  One is Holly's group of four friends.  Holly is the most grounded in the adult world, with a father who is also a detective.  Julia is the leader of the group, smart, out-going and protective.  Becca is shy and depends on the other girls to make up for her lack of a family life.  Selena is gorgeous and spacey, the kind of girl whom you wonder how they will make it in the real world.  One of them is connected to Chris Harper and now its time for the truth to come out.

This is the fifth novel in the Dublin Murder Squad series.  Tana French writes compelling mysteries that delve deeply into the relationships of those involved in criminal cases, and in the relationships of the police among themselves.  The reader is drawn into the case as it unfolds and back into memories of when your friends were your most important touchstone in life.  This book is recommended for mystery readers.