Number 18 (I think) in Randy Wayne White's "Doc Ford" series of thrillers. The reviewers at Amazon are surprisingly brutal. I liked it fine, though.
Doc's buddy Tomlinson drags him to a trailer park mostly inhabited by illegal immigrants from Mexico and Guatemala. It's to help out 13-year-old Tula, a girl posing as a boy. But they never get much of a chance to accomplish this, as an old drunk is attacked by a large gator. Ford and Tomlinson pull off a peril-fraught rescue, putting them on the bad side of Harris Squires, the park proprietor, who's deeply involved in illegal drugs (steroids, etc.) and perverted porn. In the confusion, Tula vanishes.
Unfortunately, Tula has witnessed Squires engaging in very bad behavior with a corpse. This puts a bullseye on her. But Tula believes she has a hidden ally on her side: she speaks with Joan of Arc. To the reader, that seems like a pretty thin reed to rely on for survival. Still, the plot works itself out in totally unexpected ways.
Oh, yeah: Doc gets a girlfriend. We'll see how long she lasts.
Unusually, only about half the book, maybe less, is told from Ford's first-person POV. The rest follows Tula, Squires, and Squires' nasty double-crossing retinue as they pursue their holy/unholy goals.
Quibbles: the book has that padded-to-meet-a-contractually-obligated-page-count feel, could easily have been cut down to half its length. The copy editor was sloppy: I caught a couple of howlers without looking for them. And Mr. White has an annoying habit of starting his narrative, then backing up a few minutes/hours to tell what happened immediately before, then continuing on. Please.
Still, an honest page-turner, and I enjoyed the unusual plot.