This is the 2004 entry by Will Thomas, his first of a series. It is the story of a detective operating in London in 1884 who brings in an assistant. No, it is not Holmes and Watson. While Thomas is a Holmes enthusiast, this is the account of Cyrus Barker and Thomas Llewelyn. The author wanted to dirty-up London and have his heroes engage in bloody battle in the grim streets; he succeed.
This story deals with the unrest created by a substantial influx of Jewish immigrants. A murder by crucifixion of a Jewish teacher set off unrest on both sides of the immigrant-religious line. Llewelyn did not realize when he accepted the position that promised, ‘some danger involved’, just how dangerous it could get.
I enjoyed the book and expect to read the next in the series. Yes, Thomas does mix Holmesianisms into the story, but mainly, Barker and Llewelyn are believable in their own rights.