The Death of Faith by Donna Leon (UK edition)
Normally I would not suggest a book that is in the middle of a series, but the way that Donna Leon writes makes it a good introduction to the labyrinthine world of Vienna. Commissario Guido Brunetti comes to the aid of a young nursing Nun who has runaway after suspecting five of her elderly patients have been murdered. The readers are introduced to the inner workings of the church and the various groups connected it to. But while the deaths are suspicious, there is no evidence of criminal activity, and yet something sinister seems to be occurring. But when corruption is the rule of law, how can one fight against it?
Quietly in Their Sleep is volume five of a 30 volume series. The first volume was published in 1992 and the latest in 2021. Oddly enough, these books, by the author’s request, are not published into Italian. If you are looking for a thought provoking, slow burner series, this is a good one to read.