i read it forever ago, and its stuck with me since so i've finally decided to look it up. i don't believe it was the first in the series, but i honestly can't be sure and i'm so sorry for how much of this is tentative. wish i had more solid detail to give
everything i remember:
•detective book about a man who is supposed to find (i think) a video tape. overall tone was gritty but comedic noir (to be fair though, i was reading it in 6th grade so it may not have been THAT gritty). kind of adult, i remember some kinda scandalous scenes and cussing but nothing too shocking.
•set in a world with demons, magic, some sort of extra-dimensional/extra-terrestrial beings (i clearly remember a Queen-Someone who had weapons that came out of the skin on her arms), and humans
•main character (detective) eventually meets up with ex(?) girlfriend, who is a demon (possibly a succubus?) and also a journalist. she says "lick my scabs" to someone, which really stuck with me
•at some point, there is an amusement part fight/chase sequence with Detective Man and Demonic Ex(?) vs A Bad Guy
•there is a tape involved rumored to be footage of hell (spoiler: it is just a bad dream someone recorded)
•a man makes a finger gun and shoots it at some background character, who actually dies as if shot. this was done to prove his finger gun actually worked and wasn't a joke
•the book itself was a white hard cover when you took off the dust jacket
•i read this somewhere between 2008-2010