I am the Only Running Footman by Martha Grimes

A fairly obscure mystery that mostly deals with a series of murders, many suspects and only in the last few pages solves everything. Features a crusty Scottish inspector who doesn't seem to do anything, is disliked by everyone, and in the end others solve the case and he purports to have known it all along to the complete impatience of this reader. The author has a good reputation but probably not from this book.