Faithful Place by Tana French
When he was 19, Frank Mackey planned to run away and move to London with his girlfriend Rosie Daly. This was because they lived in Faithful Place, a no-count, no-shot, no-hope neighborhood in Dublin. The night they were to make their escape, Rosie never showed, and she was never seen again. Frank got out of Faithful Place anyway and became a detective, while his parents and siblings stayed behind and got older and angrier. Now, two decades later, builders have found Rosie's suitcase hidden in an old fireplace in a falling-down house in Faithful Place; the cold case of her disappearance is suddenly hot again, and Frank is the man to solve it. But in Tana French's story, to do that, he has to go back to where he came from and face everything he left behind.