Darkly Dreaming Dexter, by Jeff Lindsay
This is the first of the Dexter books by Jeff Lindsay. I'd heard good things about the series on Showtime based on these books and got the first season off Netflix and quite enjoyed it so of course I had to check out the books.
It's a little odd in that the protagonist is a serial killer so it obviously isn't for everyone.
The entire first season of the show is based just on the first book which I really liked 'cuz it ended up being a much better adaptation of a book than usually happens since they had more time. They actually added some to the show that wasn't in the book.
There were also some fairly important changes regarding who's dead (and who isn't) at the end of season one and at the end of book one. I haven't read the second book yet to see how that affects the differences between season two and book two.
I liked the book a lot. It's definately weird though, since it's written in first person and I found myself identifying with the guy. It's a little odd when you discover you're rooting for a serial killer.
Mostly it deals with the Ice Truck Killer and figuring out who he is.