The Taker's Stone
Fischer isn't thrilled to be spending a month with his outgoing cousin, David. He would much rather stay with his mother, a museum curator and the only person who understands that, even if he is not a very active boy, he still has interests. Instead, he finds himself constantly being roped into David's crazy schemes, though he is careful to never go too far- except for one time, when he makes a mistake that throws two worlds out of balance.
I only read this book because the library didn't have the book I wanted to read- I really didn't think it would be good, and the inside flap did nothing to boost my opinion. To say that the summary is cliche is to put it mildly- I can think of several other books one could attach that summary to without anyone being any the wiser- and that does The Taker's Stone an injustice. While some elements are derivative, there are others, like Thistle, that are original and, in my opinion, really awesome.
This book has everything that is good about urban fantasy.