UGLIES by Scott Westerfeld

Tally Youngblood is one of the most daring of the Uglies, and her imaginative tricks have gotten her in trouble with the menacing department of Special Circumstances. She has yearned to be pretty, but since her best friend Shay ran away to the rumored rebel settlement of recalcitrant Uglies called The Smoke, Tally has been troubled. The authorities give her an impossible choice: either she follows Shay’s cryptic directions to The Smoke with the purpose of betraying the rebels, or she will never be allowed to become pretty. Hoping to rescue Shay, Tally sets off on the dangerous journey as a spy. But after finally reaching The Smoke she has a change of heart when her new lover David reveals to her the sinister secret behind becoming pretty.