Tally Youngblood has just given herself up to become a Pretty. Now she's living the good life: going to parties every night, getting everything for free, and so on. What she doesn't know is that she's got brain damage. Everything in her brain about the Smoke has been twisted so that she can't remember what really happened there. And she's fine with that, until she gets a strange package from someone called Croy, containing two pills, and a letter from herself giving her permission to take them. Tally is very hesitant at first, but her new boyfriend convinces her to take them. They take one each because Tally is such a wimp she doesn't have the guts to take them by herself. What she doesn't know is that they were supposed to be taken together. One has things that eat your brain, and one has things that kill the things that eat your brain. Now Zach is having his brain killed slowly. And Tally just cured herself. You know. As it happens.
(*SPOILER*) So on, the story progresses, and then just as you're thinking, okay, just smooth cruising from here, Shay, duh, gets jealous because Tally gave Zach the pill and not her. So she seperates herself from Tally and becomes a Cutter, people who cut themselves to get "bubbly" (where their mental fog clears and they can think clearly). And then she gets so jealous and weirdo that she waltzes up to the evilest evil person in the whole series, and says "Please make me a Special", the evilest group in the series. So she becomes a special, they catch Tally, and she becomes a special. (*END SPOILER*)
This book really makes you think about what perfection means. And makes you think about whether you would prefer to be clear-minded, living in the wilderness and "ugly" (even though we all know "uglies" are just normal people), or beautiful, partying all the time, and brainwashed? Does it matter?