I gave this book 4 stars, but it is difficult to rate a story that is only halfway finished. Castle Noir will be out next fall to finish up the story. Fair warning: this book ends with a cliffhanger and characters in transit and danger. It is much darker than the previous Irene Adler novels. The 'noir' in the title is justified because there is a very suspenseful and almost horror like feel to the book. This certainly could be due to the subject matter (is Jack the Ripper loose in Paris?) Sherlock Holmes also appears more in this book than the previous ones. Buy and read the book if you do not mind not knowing what happens until next fall.