In truth, Dr. Ragostin doesn't actually exist. He and his reputation are entirely made up as a means for Enola to make a living. As Ivy Meshle, Dr. Ragostins's assistant, she is able to take cases to find whatever is asked. Like her much-older brother, Sherlock Holmes, Enola employs various costumes and identities to help her make her way through Victorian era London.
This case involves looking for a missing girl, Lady Cecily, who appears to have runaway or possibly eloped, a possibility that is so shameful that her father and the police have tried to cover it up so as not to disgrace her family. The only person who doesn't believe it is her mother. Enola hears of the case by coincidence from her brother's dear friend, Dr. John Watson, who comes to Dr. Ragostin to get some help on another matter. What follows is a fairly dark situation involving a possible serial killer, kidnapping, and abuse.
I was a little surprised at how dark and scary this was, especially for a Young Adult novel. Not that anything was extremely graphic; it was well-done in that sense. I had a hard time believing the level of maturity that Enola shows at some points in the story and her lack of naivete in other situations. The Sister of the Streets was one point where I struggled with credibility but Enola's perseverance and her dogged pursuit of the bad guy were exciting and kept me reading. I also enjoyed the ciphers and the second storyline of Sherlock's pursuit of his sister. I will be reading the next in the series to see how Enola is doing.