Buy this book

[f4f3]

Vellum, by Hal Duncan.

I could give you lots of reasons, but once you've read it you won't need them. So just save us both some time and go buy it.

http://www.amazon.co.uk/exec/obidos/ASIN/1405052082/qid=1126011750/sr=2-1/ref=sr_2_11_1/026-9065062-7133266