The Beautiful Mystery (Chief Inspector Gamache #8) by Louise Penny (Minotaur hardcover, 28 Auguest 2012).
The Beautiful Mystery is the first of the Inspector Gamache novels that doesn't take the reader to the village of Three Pines. This story takes place in the monastery of Saint-Gilbert-Entre-Les-Loups, located on a tiny island in the forests of Québec.
Inspector Armand Gamache and his assistant Jean-Guy Beauvoir are allowed to enter in order to determine the identity of the murderer. They find a group of men who appear to be serenely going about their business, but are in reality shaken by the crime and suspicious of their fellows.
This is the ultimate locked room mystery. It's constructed so well that the reader is almost certain it cannot be solved, yet knows deep down that Armand Gamache can find the answer to any problem, no matter how many obstacles are in his path.
Ms. Penny is a skilful author, unafraid to take chances with her characters and story, as we have seen in every book of the series thus far, and she does it again with this one. Despite the peaceful setting, there's a lot of action here, but in your rush to learn the identity of the murder, don't forget to read slowly enough to savour the brilliant prose.
FTC Full Disclosure: I borrowed this book from my local library.