I purchased this thinking the titular Ghost was the same character from the Batman: The Animated Series episode "Beware the Gray Ghost"—one of my favorites. It was a great story where we find out Batman patterned a lot of his approach to crimefighting from an old TV show, The Gray Ghost. (Even cooler, the Ghost was voiced by Adam West, a nice nod to Batman history.) Sadly, although the art on the cover of Ghosts of Karnak seems to support this, the Ghost from the novel clearly isn't the Grey Ghost I wanted.
Set in a steampunk-inspired 1920s New York City the plot finds the Ghost initially fighting mobsters, but they take a back seat when a mystic religion that wants to destroy Manhattan is uncovered. The book is surprisingly violent, with deadly force seemingly the only thing ever used—"Batman doesn't kill" is a mantra not shared by the Ghost. To that end, the Ghost uses explosive rounds in his gun rather than regular bullets, that burst targets "chests like glistening, blooming flowers." Resurrected ancient Egyptian gods, sentient baboons, and living statues feature in the climax; while interesting, they completely pulled me out of the world and story. Overall I found this book to be disjoint and disappointing; but to be fair, I went into it with a very different expectation than what I found.
Her name was Autumn and like the season that had invested her with both name and temperament, her apperance heralded the onset of a fall.