Well, Neonomicon is even more disturbing than I remembered it being when I read it as it was being serialized a couple of years ago.
Basically, Neonomicon is best described as HP Lovecraft crossed with Silence of the Lambs. Two FBI agents get assigned to a case that involves serial killings that have a connection to the writings of HP Lovecraft. Halfway through, the story and characters (and readers) are taken to some very dark, disturbing places, definitely a very adult creation, but as with Alan Moore and Melinda Gebbie's Lost Girls, one can see Moore's mastery with the written word, characters, and big ideas. economic on isn't going to be for everyone, some may even say that the sex elements within are gratutioutious and horrific and while those would be valid arguments, the way they are presented are very much integral to the overall story. Just don't make Neonomicon the last thing you read or experience before you go to sleep.