"Specials" - Scott Westerfeld
(from the inside flap)
"SPECIAL CIRCUMSTANCES" the words have sent chills down Tally's spine since her days as a repellent, rebellious ugly. Back the Specials were a sinister rumor--frighteningly beautiful, dangerously strong, breath-ta kingly fast. Ordinary pretties might live their whole lives without meeting a Special. But Tally's never been ordinary.
And now she's been turned into one of them: a superamped fighting machine, engineered to keep the uglies down and the pretties stupid. The strength, the speed, and the clarity and focus of her thinking feel better than anything Tally can remember. Most of the time. One tiny corner of her heat still remembers something more. Still, it's easy to tune that out--until Tally's offered a chance to stamp out the rebels of the New Smoke permanently. It all comes down to one last choice: listen to that tiny, faint heartbeat, or carry out the mission she's programmed to complete. Either way, Tally's world will never be the same.
This is the third book of a series. Also the last book, so far, I can see another one coming, maybe. Tally and Shay are reunited in this book. They are both Specials, they are called Cutters, because they cut their selves to keep the "icy" feeling they crave. They are also out to get the Smokies. They are sent to find their new place and destroy it. But once they get there, they become involved in a war which Dr. Cable has used them to start. Shay and the rest of the Cutters have had the cure, but Tally is the only left with her Special skills still in tact. Tally fights to "rewire" herself to the way she was when she was an uglie. She also finds David again and they both are together keeping the wilderness wild.