I have spent this week reading more of Louis Bayard. The Black Tower was his third mystery story. The first is "Mr. Timothy",set in 1860 London, featuring the now-grown Tiny Tim from "A Christmas Carol." A very unusual and excellently done story - I liked this almost as much as "The Black Tower." The second book I read was "The Pale Blue Eye", set in 1830's New York, at West Point, where a retired New York police constable is called in as a private consultant to a gruesome murder of a West Point cadet, and enlists the aid of Private Fourth Classman Edgar Allen Poe. Of the three, this one was the least satisfying, but the portrayals of the male characters, as expected, were uniformly fascinating.
Interestingly enough, he is openly gay, partnered, with a son, and his previous novels were gay romantic comedies that have positive reviews, at least as far as Amazon is concerned. Unfortunately, the gay romances do not appear to be in print or available by ebook. I'm still debating about whether to buy them as used paperbacks.