The first 30 pages or so could be a straightforward, gritty police procedural featuring undercover cops. But suddenly and dramatically the main characters' universe is pushed askew. It's hard to describe exactly what results, but if you imagine a combination of a modern version of The Devil Rides Out, a dark police procedural and a sprinkling of Neil Gaiman's Neverwhere and you might come close.
Four individuals - a detective inspector, two recently undercover officers and an intelligence analyst - are pulled into a world where a kind of magic dependent on the sheer depth of London history makes the impossible happen. This is genius on Cornell's part. Pretty much always in this kind of urban fantasy it's a group of unqualified misfits (think the Scoobies in Buffy) who have to sort out the occult threat. The authorities get left out of it, because they just wouldn't understand. But Cornell makes those misfits work for the police, and so they are trying to use traditional policing methods alongside a gradual growth in understanding of the arcane requirements needed to deal with an ancient character who is obsessed with West Ham Football Club.
If that sounds a fairly light concept, it's a contrast to the darkness of the theme, where their main foe's power is derived from boiling young children alive. And that's just the beginning of the horror.
Just occasionally I found the inner monologues of the main characters hard to follow, especially when they were beginning to get a slight feel for what they were facing, but were still mostly confused. But that really didn't matter as the book has enough page-turning momentum to keep the reader moving on.
All in all, the best fantasy book I've read all year, and I'm delighted to discover there are two more books featuring the same police group to get my teeth into. Recommended.
London Falling is available from amazon.co.uk and amazon.com.