Maddy and Az go on to explain how they left the city and made themselves a little ugly. Some parts of the plastic surgery can't be reversed. Like, they keep their perfect eyes, lucky them.
They left the city to found a town that didn't have any pretty people to see what that sort of society would be like.
Maddy and Az can reverse the physical process, but they haven't found out how to reverse the brain lesions. It's hard to get funding to reverse a secret surgery when the government likes to keep that surgery secret.
Tally thinks back to her parents and the new pretties she's seen. True, they've all been a little dumb. (Or as Will Smith put it, parents just don't understand.)
This all rocks Tally's world—in a bad way—but David explains that he couldn't let her go back to the city without hearing about the brain damage.
On the way back into the Smoke, David also tells Tally he thinks she's beautiful. Even the wounds she had from her rough hoverboarding in the city were attractive to him, since they meant she had a story to tell.
He even thinks she's more beautiful than Shay, which is kind of an uncomfortable moment. Let's rank all our friends by how pretty they are. Yes, that's a great friendship-building moment.
But then he gets back to afterschool special territory by telling her that what's important is what's inside her.
And they kiss.
And somewhere in that long chapter, Tally decides not to betray the Smoke by calling Dr. Cable. She runs to the center of the town and throws the heart pendant on a fire. Which is so Tally—dramatic and sudden and involving fire.
David then goes for a walk and Tally goes to the dorm to sleep.
When she wakes up, Special Circumstances has invaded, which means we need not just a new chapter, but a whole new part.