The second in the 4 book Julian Kestrel series of mysteries set in 1820's England.
This series of books have some of the more interesting and creative mysteries and solutions. I have yet to guess the culprit before the conclusion. The mysteries tend to be constructed of many small mysteries, in this case lots of unknown identities, that must be solved before reaching the ultimate solution.
I didn't think that the characters introduced in this book were as interesting as the first book and that knocked it down a few notches. Sally was your stereotypical plucky heroine which I think to me seemed even more like a charicature because she spoke in cockney slang.Which is likely completely realistic for her character but for some reason I have a hard time taking it seriously. And while I like that the author tries to include a little romance in her books - the relationship between Sally and Julian was just odd and made little sense in light of Julian's character.