Ruin, by Dervla McTiernan

A seeming suicide leads to the reopening of a 20-year-old overdose case; were they both actually murder? Detective Cormac Reilly must investigate Maud Blake, the woman who links both cases. He was the officer on the scene of the overdose death, in his first months on the job. What did he miss? At the same time he has to navigate the complex politics of the Galway police department, as a recent transfer in from Dublin. He has learned a lot in the last 20 years of policing and he will need all his experience to get to the bottom of this mess. McTiernan weaves a dark tale of abuse, tragedy and treachery, deceit and corruption – and that’s just the cops. The slightly world-weary Reilly is believable and relateable, stepping down in his career to support his partner. His move back to the west country brings personal and professional challenges as he works out who he can trust. A sequel has been published in what looks likely to be a satisfying series.