This is another detective series set in Ottoman Istanbul, albeit later in the 19th century than Jason Goodwin's Inspector Yashim series. I enjoyed it, but it was subject to the same problem with the recent Goodwin books – it is sometimes difficult to follow exactly what is going on, and the author tends to submerge the story in the period details. Not that I don't enjoy that, but it can make the read a bit tedious.
More importantly, however, the book is virtually unreadable as a story because the action jumps around in time and perspective, and it is exceedingly difficult to keep track of all the characters – all-female – who are relaying bits of the story. It doesn't help that part of the plot involves the fact that the murders are repeated, so the facts preceding and following the drowning of a young English governess in Istanbul do not necessarily refer to the same event.
Again, if you are just reading for period detail, this isn't so much of a problem.