It's a mystery to me (and a large reading public) why Caleb Carr has not followed up on his two wonderful novels (1994) and (1997). Maybe it's because the two more recent novels, and were so badly received. Nevertheless ...
The first two were fun for anyone who loves mystery histories, because they both involve some historical characters we love to meet in circumstances such as these. Theodore Roosevelt and J.P. Morgan have starring roles in Alienist. Angel brings in Clarence Darrow, Cornelius Vanderbilt II, and Elizabeth Cady Stanton as well as TR, reprising his role from Alienist.
The actual star of both novels is the alienist himself, Dr. Laszlo Kreizler, a fictional character who uses the new technique of fingerprinting as well as his own field of psychology. Apparently, "alienist" was a 19th century term for "psychologist." I found this definition: "A physician who has been accepted by a court of law as an expert on the mental competence of principals or witnesses appearing before it." An alternative definition as "a person who practises alienism," was termed "obsolete." Which made me wonder if the first definition is still in use somewhere today.
I can't say the prose style was overwhelming, but I can forgive much for Carr's delicious potpourri of history and mystery.