The story is set in Japan. The city functions with a unique economy, one based on popularity. Each citizen has their own "feed", a place to post (or "kick") gossip and opinions, and the more people that pay attention to a person, the higher their "face rank", or popularity ranking.
Aya Fuse escapes her dorm with her hovercam, Moggle, and flies toward Prettyville. She is looking for a young lady named Eden Maru, a famous hoverball player, and who Aya had seen mag-lev surfing with a small group of girls. Aya, whose face rank is extremely low (making her an "Extra"), wants to "kick" a story of this extreme feat and in the process become famous herself. While following Eden, she stops at a party. She runs into Frizz Mizuno, a moderately famous Pretty. Mizuno says that he likes Aya's nose, which is ironic as Aya has yet to undergo the Pretty operation and believes her nose to be too large. Aya leaves without telling the boy her name, in embarrassment of her face rank, and runs after Eden.
After catching up with Eden, she realizes that Eden knew she was being followed. One of Eden's groupies pushes Aya into the water and the leader, named Jai, puts a lock-down clamp on Moggle. The girls fear that Aya might kick their story and raise their face ranks, which they do not desire as they wish to stay underneath the radar. The girls reveal themselves as a group known as "The Sly Girls" and give Aya the choice to either; drop Moggle in the water and join them, or take Moggle and leave. Aya chooses to pretend to join the group and vows to eventually gather enough footage to kick their story.
The next day, she goes to visit her brother Hiro, who is another kicker, and his friend Ren Machino. Once she gets to his apartment, she realizes that Hiro has made the top thousand. Aya unsuccessfully tries to explain the Sly Girls, but this is impossible as they are practically a myth, and used as an explanation whenever some prank occurs that no one fesses up to. While Hiro is browsing the feeds, Aya recognizes Frizz Mizuno and learns he became famous by starting a clique called Radical Honesty, where they receive brain surgery to force themselves to constantly speak the truth, meaning he was not being sarcastic when he said he liked her nose.
Aya explains her situation to Ren and he agrees to help her get Moggle back. Aya receives a ping (message) that tells her to meet the Sly Girls the next day where the mag-lev meets Uglyville. She does so, meets a couple of the Sly Girls and proves her veracity to not be a kicker (all the while wearing a spy-cam on her dorm uniform). They surf on a mag-lev train, but the fun stops when the train stops in the middle of a tunnel and they see some strange inhuman-looking figures transporting large metal cylinders into a secret hole in the wall.
Aya gets Moggle back from the large body of water and meets up with Frizz, who has found out her identity. They have a heart-to-heart talk about fame after she cleans up from her retrieval of Moggle. Aya does more surfing trips with the Sly Girls and finds that they change their nicknames every so often to keep their face ranks low; for instance, Jai has changed her name to Kai. After exploring the secret rooms beyond the hole in the tunnel, she interviews Eden and finds how she can keep the Sly Girls secret while being so famous all the while recording their escapades.
Aya gets back and finds that she herself was secretly filmed on a hovercam while talking with Frizz. She was covered in slime during the conversation and looks very embarrassing on the camera. She is being referred to as "Slime Queen" by various people and her face rank has driven up. Unfortunately, this means that she is temporarily banned from the Sly Girls. While she bides her time, waiting for her face rank to fall, she compiles all her footage into a video for her to kick, and visits Hiro and Ren where she finds out that she has been sneaking around mass drivers which could easily be used as weapons. She decides to tell the Sly Girls about this.
When Aya meets them again, she finds that they already knew of her treachery and had even realized the truth about the mass driver themselves. Kai, now Lai, launches Aya out of the mass driver - with a homemade parachute - as a last trick. While Aya hikes back the Sly Girls are leaving the city to avoid fame. Aya returns home compiles the rest of her footage and gets ready for a party that Hiro is taking her to, so that she can kick the story about mag-lev surfing and the secret mass driver. Aya kicks her story and becomes famous. After enduring countless questions at the party, Frizz informs her that her face rank is now 17. Then Aya gets a ping...from Tally Youngblood herself.
Tally's ping says to run and hide. After many attempts to "hide", they go to Shuffle Mansion, where it is so secure, not even Moggle can go in. Eventually, Tally, Shay, and Fausto find them and take them to run away on hoverboards from the "freaks" that have built the mass drivers. These freaks have surgery that makes them like monkeys. Although Tally cautions Aya not to, she sends a transmission signal to Moggle, that Tally for some reason later boosts so that moggle can keep up. Eventually, they are caught and it is revealed that Tally had wanted to be caught all along. In the ship they have been abducted in, one of the Inhumans identifies himself as Udzir. Frizz, however, ruins the plan by revealing that Tally is on the ship because of his radical honesty.
The group runs away, and after many more adventures, meet up with David. They eventually get to the freaks' base and find a line of missiles. After being caught by the freaks again, Aya is confronted with a reprogrammed version of Moggle, along with Udzir and Andrew Simpson Smith. Aya, Frizz, Ren, and Hiro find that the freaks, who call themselves Extras (capital E) for Extraterrestrial. Since they are planning to be living in close quarters in little gravity and light in space, feet are unnecessary, extra vitamin D absorption is important, and normal depth perception is not needed, so the bodies are modeled differently. The mass drivers were used to get the metal into orbit and the "missiles" are actually ships. The colonization of space is going to be used so that the population expansion can be redirected into permanent orbital habitats before it is too late and further colonization of Earth can be slowed by the metal shortage. However, Tally is unaware of this and starts destroying the ships. Aya tries to stop her, taking a risk as Tally still has destructive, Special brain wiring. Eventually, she is convinced when Frizz explains because she knows he can't lie.
The whole gang goes back to the city to go to the Thousand Faces Party, where only the face ranks 1 to 1000 are invited. Udzir is face ranked in the 100s so people joke that he is the only Extra that is not an extra at all. Aya's face rank is now 3. She finds Lai at the party, who has a face rank of 957. She tells Aya that Eden created a smart matter injection that Lai put in the cake, and when it is cut, it will explode so that everyone is covered in cake. Lai tells Aya that this could be a good story for her, and not to tell anyone; she is also joining Udzir to become an Extra. Aya talks to Frizz and finds that he is going to quit Radical Honesty. She sees Tally walking off with David. In the end, Aya goes with Frizz to watch the cake being cut.