|The appropriately creepy cover of In The Woods.|
I'm reading Broken Harbor right now, and it's one of those books that keep you up at night (which is bad only because I'm sleeping terribly these days anyway). My favorite in the series was The Likeness, probably because it had a female protagonist and had a slight paranormal feel to it (even though it's not paranormal at all).
You don't need to be a fan of detective novels to read these books. You just need to like books that are incredibly well written, involve realistic, multi-layered characters, and keep you guessing all the way to the end. And I'm pretty sure that's everyone.