Broken Harbor by Tana French

Detective Mick "Scorcher" Kennedy and his newbie partner, Richie Curran, are assigned the case of the Spain family, who live in a half-empty new housing development that's gone bust in Brianstown, outside of Dublin.  Pat Spain and his two young children, Emma and Jack, were found dead in their home, while Pat's wife, Jenny, seriously injured, was rushed to the hospital.  Kennedy and Richie don't know if Pat or Jenny were responsible or if it was an intruder. The presence of several baby monitors, video cameras, and holes in the walls only adds to the mystery.  Kennedy is thrilled to be the lead investigator on this high profile case, figuring it should be a straightforward investigation--but as it progresses he and Richie find they're left with more questions than answers.  Kennedy's own memories of Brianstown (called Broken Harbor when he vacationed there with his family when he was a child) are traumatic--his mother committed suicide there. Now, his younger sister Dina is continuing on a downward spiral into mental illness, adding to the pressure that Kennedy is putting on himself.  In Broken Harbor, the fourth book in the Dublin Murder Squad series, French has written a book that's even better than her last.  It's a police procedural with psychological depth that keeps the reader guessing until the end.  So so good....