Many reviews labeled this novel an historical mystery, but I am not sure mystery is really the right category. The Alienist tells the story of the blossoming field of criminal psychology as the main characters seek a serial killer in 1896 New York City. From the outset the reader generally knows whodunit, the main question is WHY these murders are happening and based on this information can our heroes predict the next attack in order to stop the killer.
Carr does a great job bringing the Gilded Age to life through the sights, smells and activity of the late 1800's. His descriptions of restaurants, operas and NYC ghettos bring the story to life. He has included so many facts of the time as to make the created characters seem real. One aspect I found particularly intriguing was his use of Theodore Roosevelt as NYC police commissioner; he included such details of Roosevelt's actual life including some aspects of his childhood, college studies and other information maybe little known to most readers. Carr also includes other real people like James Riis, JP Morgan and William James who each played a significant role in NY during this period. I found myself googling these people to get additional information. This book brings out the historian in the author.
The book was lengthy (500 pages, small print) but rarely seemed long. Many of the details relating to the murders were grotesque (I could have done without that) but the facts that attribute to the development of criminal science and forensics that are prevalent today are very interesting.
If you're a fan of historical fiction this is one of the better ones I've read. But be warned, the forensic details are gruesome and the general theme of serial killer hunting young boys is not pleasant either.