A very deep,dark,rich mystery with lots of threads that come together for a heart-pounding conclusion. I loved it. One of the best historical mysteries I have read in quite some time.
Robertson manages to give all of her characters, even the secondary ones, depth and personality. I was especially fond of Mrs. Bligh, the Tarot reader, with her dog Boyo. Our main characters are no paragons--Harriet and Gabriel have their flaws as well as strengths, and the author is not shy about bringing them to our attention. Her attention to the historic detail is very good, without being didactic. I could believe myself in London in the fall of 1781--all the little touches were there.
Though this is the second in an on-going series, the author provides enough back-story to make it accessible to readers who have not read the first. And if you haven't read the first (Instruments of Darkness), then you have missed a treat.