The glass room / Ann Cleeves.

DI Vera Stanhope is not one to make friends easily, but when one of her neighbours goes missing, she feels duty-bound to find out what happened. It's an easy job to track the young woman down to the Writers' House, a country retreat where aspiring authors gather to work on their novels. But things get complicated when a body is discovered and Vera's neighbour is found with a knife in her hand. Calling in the team, Vera knows that she should hand the case over to someone else. But the investigation is too tempting, and she's never been one to follow the rules. Working with Sergeant Joe Ashworth, she starts the hunt for a murderer who has turned killing into an art form.