Uglies is a young adult science fiction novel set in a future world where everyone receives extreme plastic surgery at the age of sixteen to become "Pretty." Tally Youngblood rebels against this practice, aligning herself with a group of anarchists known Uglies, who believe that the beauty standards enforced by society are wrong and are fighting to overthrow the current government. The narrative explores themes of adolescence as well as critiques society standards and expectations.
Three hundred years in the future, the government provides for everything, including plastic surgery operations. Everyone on their sixteenth birthday receives the“pretty” operation which transforms them into the society's standard of beautiful. After the operation, new Pretties cross the river that divides the city and lead a new life with no responsibilities or obligations. There are two other operations available, one to transform Pretties into “Middle-Pretties” (adults with a job), and another to transform Middle-Pretties into "Crumblies."
Former cities have decayed after bacteria infected the world's petroleum, making it unstable. The old society, so dependent on oil, fell apart when cars and oil fields exploded and food could no longer be transported. People who lived before this catastrophe are called "Rusties."
Tally Youngblood is almost sixteen. Like every other Ugly, she awaits the operation with great anticipation. Her best friend, Peris, has already had the operation and, motivated by her desire to see him, Tally sneaks across the river to New Pretty Town. There she meets Shay, another Ugly. They become friends and Shay teaches Tally how to ride a hoverboard. Shay also mentions rebelling against the operation. At first, Tally ignores the idea, but is forced to deal with it when Shay runs away a few days before their shared sixteenth birthday, leaving behind cryptic directions to her destination, a“renegade settlement” called the Smoke, where city runaways go to escape the operation.
On the day of Tally’s operation, she is taken to Special Circumstances, a division that is likened to “gremlins” and “[blamed] when anything weird happens." Dr. Cable, a woman who is described as “a cruel pretty”, is the head of Special Circumstances. She gives Tally an ultimatum to either help locate Shay and the Smoke, or never become a pretty. Tally cooperates and Dr. Cable gives her a hoverboard and all the needed supplies to survive in the wild, along with a heart locket that contains a tracking device. Once activated, it will show the location of the Smoke to Special Circumstances. FollowingShay's clues, Tally sets off to find her friend.
When Tally arrives at the Smoke, she finds Shay, her friend David and an entire community of runaway Uglies. She is reluctant to activate the pendant and it eventually becomes clear that David is in love with her. David takes her to meet his parents, Maddy and Az, who are the original runaways from the city. They explain how the operation does more than“cosmetic nipping and tucking.” It also causes lesions in the brain to make the people placid, or “pretty-minded.” Horrified, Tally decides to keep the Smoke secret and throws the locket into a fire. However, the flames' heat causes the tracker to activate, giving away the Smoke’s location.
The following morning, Special Circumstances arrives at the camp and Tally makes an effort to escape. She does not succeed and is caught and taken to a rabbit pen, where other caught Smokies are kept, tied up. Eye scans are taken of all the captured Smokies, identifying from which city they fled. Tally is then taken to Dr. Cable, who explains how they found the Smoke. Dr. Cable thinks Tally purposefully activated the pendant. After being ordered to retrieve the pendant, Tally escapes on a hoverboard. After a long and stressful chase, she manages to hide in a cave where they cannot track her heat signature. There she finds David also hiding and together, they begin to plan a rescue.
Tally and David go back to his house, where they find evidence that Special Circumstances took Maddy and Az. David leads Tally to a secret stash of survival equipment where they find everything they need, and load them onto the four hoverboards stashed there. As Tally and David travel back to the city to free their friends, they fall in love. Arriving at the Special Circumstances complex, they discover that Shay has already been“turned” and is now a Pretty. After meeting Dr. Cable, David knocks her out and takes her work tablet, which contains all the necessary information to reverse the brain lesions created by the Pretty operation. Tally and David then free all the Smokies held in the complex. As they escape the complex, Maddy tells David that his father, Az, is dead.
Once everyone is safe, Maddy begins working on a cure using Dr. Cable’s tablet. She then offers it to Shay, who refuses, not wanting to become a “vegetable.” Since Tally feels responsible for her betrayal, she decides to become a Pretty and take the cure as a “willing subject”. To convince David to let her go back to the city, she tells him about her involvement with Special Circumstances and searching for the Smoke to betray them. While David is absorbing what Tally admitted, Maddy advises Tally to go back with Shay before she changes her mind. Once there, Tally announces to a Middle Pretty, “I’m Tally Youngblood. Make me pretty,” the finalphrase of the novel.