** spoiler alert **
Found this one the weakest of the series because a lot of the time was spent with Sally not being able to figure out what was what, when it was as plain as the nose on her face. There was also a lot of proselytizing about the ills of Victorian society, including their treatment of the poor, which is interesting, but doesn't feel germane to the story. Sometimes I felt as if I was reading a tract for socialism rather than an adventure story. And the famous bad man of the first mystery doesn't fully emerge as the scary character he seemed in mystery number one. So, interesting, but definitely not a home run.