A Hell Within (Griffin & Price) by James A. Moore and Charles R. Rutledge

I stay away from sci-fi / PI mash-ups or paranormal romance / urban fantasy featuring PI's. I do have a soft spot for true occult detectives though.
Sheriff Carl Price and ex-mercenary, now PI, Wade Griffin get involved with some pretty dark forces in the town of Wellman. Luckily they're pretty tough guys and get some help from occult detective Carter Decamp.
There's lots of Easter eggs here for occult detective fans. Wellman is obviously named for the creater of several occult detectives, Manly Wade Wellman. And Wade Griffin of course as well. Decamp probably owes his name to L. Sprague Decamp, author of some cool Conan books.
Anyway, this is a lively mix of a PI story and a fantasy / horror story. The creatures are pretty cool, there's a lot fo fast-paced action and the characters are very cool. This probably would do great as a comic book as well.
All in all, I loved the ride.