I really enjoyed this book - Enthoven tells his story with a lot of pace, humour and enthusiasm and it really made me want to turn the pages to find out more. At heart, it's a standard good -versus- evil plot. A secret society of magically and physically gifted humans have been working to keep a demon known as The Scourge contained within a magical prison. Unfortunately, someone has let it out and the society's head, Nick, realises that he needs new recruits to help them lock it back up again. He picks Charlie and Jack, apparently at random, from the street. Charlie, who is failing to deal with the break-up of his parents' marriage, passes a test and develops magical powers, evidenced by the sudden appearance of a sinister black tattoo on his body. He takes over as leader of the group (which is a surprise to Esme, who has been raised by one of the group's members and trained all her life to assume leadership. Jack is just ordinary and trails after his magically gifted friends who have super-fighting skills. Together, they work to recapture The Scourge, who is revealed to have a sinister plan all of his own and who is picking off the remaining members of the society with surprising ease. The battle against him takes all three teenagers to Hell.
I loved Enthoven's depiction of London - he's comfortable with his location and has his characters move around it with ease. I also enjoyed his depiction of Hell, which was something I had never seen before (effectively, he makes Hell a living location, pitching it on the back of a gigantic dragon). He doesn't stint on the gore and ew! factor (there's a particularly horrifying scene involving Jack drinking demon bat vomit that's lovingly drawn out and makes you laugh even as it makes you gag) and he has a wide variety of demonic characters, some good - some not so good, who are vividly brought to life (my favourite being the Chinj who helps Jack). I also thought that he brilliantly captures the inarticulate dialogue between teenage boys, particularly when they're discussing emotional issues.
However, there are flaws. I'm not sure whether Enthoven really strikes a balance between his three characters and there are times when each seems a little stereotypical (Charlie with his anger, Esme with her anger and Jack with his ordinariness) and I think that some readers may find the introduction of Charlie and Jack into the new world of demon hunting to be a little too pat whilst the despatch of the various older members of the society at times feels like a checklist of death. The biggest problem however is the ending. Without wishing to give too much away, Jack goes through a major change in the book that seems to have just gone away or not been dealt with by the book's end (even though Enthoven's taken care to establish which Jack is in trouble with his new situation) and we're never really told what the effects of this change are, beyond some broad allusions to telepathy. I was also left confused as to what was going to happen with Charlie and Esme at the end, given the way in which they each achieve their aims and the discoveries they make in the process. Enthoven doesn't really examine the aftereffects at all, certainly not for Charlie and I would have liked to see some form of resolution - although the final chapter clearly leaves the way open for further books and more adventures. Enthoven also seems to leave the way open for a love triangle between the three and I really hope he doesn't go down that route because it's been done to death in YA fantasy and I think would serve to throw up more characterisation problems than it would solve