This is a brilliantly written book about a teenage sociopath growing up in a small town in America. He's suspected he's a sociopath even before it's clinically confirmed.
He's grown up helping his family with their mortuary business and has an obsession with serial killers. Even though he thinks he may be fated to become a serial killer (his name is John Wayne after the actor but he points out there's also John Wayne Gacey and his last name is Cleaver) he tries hard to resist it.
John gives himself rules to keep his darker impulses at bay but they're never far from the surface.
It really feels like a disturbing but insightful look into the mind of a sociopath.
I'm not a fan of Dexter (not because of the sociopath thing) but if you are I think you'll love this book.
I do have one quibble though and that's the introduction of the supernatural element. I really don't think the book needs it at all and it takes away from the realism of the rest of it. I don't know if Wells thought it was necessary to have a good enough reason to let the monster out or if there was some other reason.