The first part of this book reminded me a lot of Iain Banks' The Wasp Factory as it also features a disturbed teenager and their descent into madness. There's plenty to satisfy gore hounds as you join Michael on his journey (Londoners will probably recognise a few of the locations).
But about half way through there's a twist which turns it into to creepy supernatural detective tale involving occult possession. There are certainly some intriguing ideas here.
The end result is a compelling, if nasty in places, serial killer detective story with a strong taste of Victorian gothic.