First things first: I need to mention I received this book from Goodreads giveaways. Second thing I need to mention: the blurb for it contains huge spoiler, so read it at your own risk.
London, 1875; Charles Lenox is a former private detective who works in Parliament. His protege John Dallington asked him to help with his new case: Dallington received an anonymous message asking him to meet its author at certain place and time, but the detective fell ill. Charles goes in his place and completely botches the job. His curiosity about the identity and purpose of massage's author leads all the way to Buckingham palace.
The main thing I realized after reading this book is that I miss short mystery stories - Sherlock Holmes style. The main plot and two subplots are very good and interesting, but they would work much better in short story format; there is too much filler material which can be skipped without any impact on the overall plot.
Some things made me chuckle; I do not think it was author's intention, or was it? As an example people in Parliament were complaining about London traffic - we are talking the year 1875 here; I guess the traffic problem has always been. I would imagine in came to Europe the moment the evading barbarians settle down.
As I mentioned above the short story format of this book would get an easy 5 star rating from me; as it still worth 4 stars as it is now.