One of my more recent favorite books was "The Historian," by Elizabeth Kostova. It's not light reading, the tome weighs in at a hefty 642 pages. But every single page is worth it- so much so that I've read it twice, which is more than I can say for most of my favorite adult books published after, say, 1980. This Librarian of the Dead has so much stuff to read all of the time, that I took the time to read that TWICE. Think about it.
I loved the way "The Historian" mixed horror and supernatural themes with mystery, adventure, historical fiction, and a rich sense of setting. Specifically, the book explores the legends of vampires and Dracula in relation to the main characters. If any of this has made your inner reader perk up, I highly recommend the book. Don't be intimidated by the size, it moves quickly.
For those who just can't stomach 600+ pages, or have already read "The Historian" and enjoyed it, I would not hesitate to suggest Andrew Pyper's "The Demonologist."
It's very much along the same lines, although without the historical fiction aspect. It's set in modern times, but still does an amazing job of blending horror, mystery and adventure into a heart-wrenching exploration of a father's love for his daughter.
I'm going to yoink a description from another reader, Bonnie, on Goodreads. She did a really great job of summing up the story-- better than I feel I can do-- and as we say often in the library world, let's not reinvent the wheel.
"David Ullman is a non-believer despite the fact that he has dedicated his adult life to studying demonic literature, primarily Milton's 'Paradise Lost'. When he's approached one afternoon and asked to be a witness to a phenomenon that requires his professional opinion as a ‘Demonologist’ he accepts the offer and shortly afterwards is headed to Venice, Italy with his twelve-year-old daughter Tess. What David sees in Venice will leave him questioning everything he has ever believed. And when Tess is taken, he has no choice but to accept the things he saw in order to save her from the Underworld."Some other readers have also compared this to Dan Brown novels, like "The Da Vinci Code." I hadn't considered that, but it's a good comparison, especially with the exploration of demons and all of the clues David finds himself following in order to find his daughter, and discover what the demon truly wants of him in time to thwart it. It has that mystery-adventure vibe that Brown has had a talent for (if you like his stuff).
But "The Demonologist" is more than just someone running around the world trying to solve a mystery. It's a very dark book. Not only do you have that supernatural demonic element, you've got a main character who suffers from serious depression, and suspects that his child may suffer from it too. The things David sees along his quest are not only meant to terrify, but to disturb him in a close, personal way, all in the name of manipulating him to do what the demon wants. There are also definitely some moments of cringe-worthy blood and gore, if that's going to make or break a novel for you.
I didn't know much about "Paradise Lost" myself before going into this book, so that's not a prerequisite to enjoying it. I can imagine if you are more familiar with it, that might actually help you appreciate it even more, since you'll already understand the references David makes throughout the story.
Personally, "The Demonologist" was right up my alley. If you like these sorts of genre-crossovers, and don't mind covering dark subjects, I would definitely recommend picking it up.
The Demonologist via Goodreads
Andrew Pyper's website