This is book 14 of the "Stone Barrington" series.

This note does not contain major spoilers for the book.

Stone and Holly chase Teddy Fay in St. Marks. And discover everyone is hiding something. Fay has three separate identities there well-established, and local confederates.

A supporting character is "Jim Tiptree", the local CIA station chief. "James Tiptree" is one pseudonym that Alice B. Sheldon used for her science fiction stories. She did serve in the CIA briefly, in the 1950s (so not at the time this story has that name active in St. Marks). The character is clearly male; since gender identity is so deeply at the core of the James Tiptree story, that's a little bit shocking.

It could be entirely a coincidence, of course. Sometimes I wonder whether authors I'm reading outside SF and fantasy have read some of the same things I have, mostly inside SF and fantasy. I think of the Tiptree story as very much within our little SF and fantasy world. (I've emailed him via the address on his web page to ask, just out of curiosity; and I got back a prompt response saying "It's a coincidence." Good thing I considered that one of the possibilities from the beginning!)