Uglies is a book series by Scott Westerfeld for young adults. Westerfeld originally intended for Uglies to be a trilogy. However, after publishing the series' first three novels, Uglies, Pretties, and Specials, he ultimately wrote an additional fourth book, Extras. This fourth book is dedicated “[t]o everyone who wrote to me to reveal the secret definition of the word ‘trilogy.’”
The first three novels focus on the exploits of Tally Youngblood. In the post-apocalyptic future society where Tally lives, teenagers, upon reaching their sixteenth birthday, undergo a surgery to mold them into a so-called “Pretty.” When Tally’s new friend Shay runs away to the Smoke, a secret refugee for those who oppose the city’s government, the future of Tally’s own operation becomes uncertain. Dr. Cable, the head of the mysterious Special Circumstances, cuts Tally a deal: betray her friends and help the city locate the runaways or remain an “Ugly” forever. When Tally joins the Smokies, she learns a chilling truth: the surgeries that the city performs are not just intended to render its inhabitants beautiful. The city also puts lesions into the minds of the “Pretties,” making them a shallow, unintelligent, and ultimately easier to control population. Over the course of the novels, Tally struggles to maintain her sense of self within a society that literally alters how people think and ultimately succeeds in undoing the system of mind alteration.
The fourth novel centers on Aya Fuse, a girl struggling to find her place in the chaotic world after Tally frees people to think for themselves.