I'll give credit where it's due: The Devil Aspect was good for about 75% of the book. The combination of an asylum for the seriously criminally insane, the search for the devil, and a castle on the hill with a terrible reputation has the potential to be a powerful combination. It worked extremely effectively in the film A Cure for Wellness, so I had high hopes for this book.
But as books about the devil usually do, it all unraveled at the 3/4 mark. The tight tension and atmosphere that had been built, with the nice casual addition of rising political tensions on the eve of WWII, was blown on a very bizarre twist that confused more than shocked, and ended up being tropey and trite rather than mind-blowing. The internal logic of all I'd read just collapsed in on itself as Dr. Victor Romanek desperately searches for the connection between his patients and his theory of the so-called "devil aspect" that afflicts men's minds and makes them do unspeakable things (murder, cannibalism, you know).
The biggest problem with this book, without intentionally spoiling anything, is that this makes the argument that all of the worst characters in history (Gilles de Rais, Jack the Ripper, etc.) are just the devil by another name. Which completely negates any sense of human agency for any of these figures, historical or fictional. Sorry, but that makes things less horrifying. Not more.
Also - can we just stop using Jack the Ripper as a cop-out for evil people? It's an overused shortcut, as are Nazis. Both of which magically made their way into this book.
K. Rating: 2/5