A Rule Against Murder by Louise Penny

In the fourth book of her Inspector Gamache series, Louise Penny fills in some of Gamache's personal history.  Gamache's family life is compared to the Morrows', a wealthy family having their annual family reunion at the same resort Gamache and his wife have traditionally celebrated their anniversary. When one of the Morrows is murdered, Gamache must sort through all the resentment and anger that has festered over the years to discover the murderer.  322 pages.