I did some googling, and was surprised to find out that Coldfall Wood is an actual ancient wood in London, England, covering 14 hectares. In this book, there are other ancient things there; ancient beings who do not like what humanity has done with the world. Beings that plan to turn things back to the way they used to be.
Coldfall Wood, by Steven Savile, is actually a sequel (the first book is called Glass Town), even though this fact is not exactly advertised on the cover, but while there was a learning curve to get the hang of who the characters were, the story was pretty much standalone.
Basically, an ancient king/goddess-consort takes advantage of a tear in reality caused by the events in the first book, and he wakes a number of his followers, placing them into the bodies of contemporary youths, all connected by an abusive foster home. This inadvertantly has the side effect of inflaming racial tensions. There are also a seres of young girls who drop into coma-like states, only to all wake up at the same time, all saying the same thing. Police find an old man alone in a house, with greenery shoved down his throat, but when the greenery is removed, he wakes up.
The story builds well, filling in details from the previous book without being overwhelming about it, and the dark atmosphere grows more and more intense. My only complaint was that while the ending was satisfactory, it didn’t quite live up to the tension that had been built. But it did leave me hitting Google, looking up elemnts of myth and geography that intrigued me, so I would call it a success.
Thanks to the publisher and Netgalley for letting me read this