Tally Youngblood is about to turn sixteen, and she can't wait. In Tally's world, your sixteenth birthday brings an operation that turns you from a repellent ugly into a stunningly attractive pretty and catapults you into a high-tech paradise where your only job is to have a really great time. In just a few weeks Tally will be there.

Anticipating this happy transformation, Tally meets Shay, another female ugly, who shares her enjoyment of hoverboarding and risky pranks. But Shay also disdains the false values and programmed conformity of the society. She'd rather risk life on the outside and urges Tally to defect with her.

When Shay runs away, Tally learns about a whole new side of the pretty world — and it isn't very pretty. The authorities offer Tally the worst choice she can imagine: find her friend and turn her in, or never turn pretty at all. The choice Tally makes changes her world forever