The Winner's Curse by Marie Rutkoski

Summary: "An aristocratic girl who is a member of a warmongering and enslaving empire purchases a slave, an act that sets in motion a rebellion that might overthrow her world as well as her heart."

Whew! What a wild ride this book is! The story progresses quickly, much more than the average first novel in a series. 

If you do read it, make sure you have the second one, The Winner's Crime, on hand - you will want to start it as soon as you finish The Winner's Curse. 

355 pages