"Special Circcumstances"... the words have sent chills down Tally's spine since her days as a repellent, rebellious Ugly.

Back then, the Specials were a sinister rumour - frighteningly beautiful, dangerously strong, and breathtakingly fast. And now Tally's become one of them: a super-amped fighting machine, engineered to keep the Uglies down and the Pretties stupid.

But one tiny corner of Tally's heart still remembers something different.

When she is ordered to stamp out the rebels of the New Smoke, she is forced to make one last choice: carry out the mission she's been programmed to complete, or listen to that faint yet persistent heartbeat telling her that something's wrong...