The novel portrays a near-future in which the feednet, a huge computer network (apparently an advanced form of the Internet), is directly connected to the brains of about 73% of American citizens by means of an implanted device called a feed. The feed allows people: to mentally access vast digital databases (individually called "sites"); to experience shareable virtual-reality phenomena (including entertainment programs, music, and even others' memories); to continually interact with intrusive corporations in a personal preference-based way; and to communicate telepathically on closed channels with others who also have feeds (a feature called m-chatting).
The setting of the novel is depicted as ecologically devastated. Natural clouds have been replaced by trademarked Clouds™, implying artificial replications due to atmospheric pollution. Bodies of water have become acidic and toxified. Human sexual reproduction appears to be no longer possible through natural means. As a result, women undergo in-vitro fertilization and have their children custom-designed.
The corporations responsible for the feed have immense power and even run the school system, which is now known as School™. Throughout the book, corporations appear to hold the true power in United States, leaving the president virtually helpless as the Global Alliance, a coalition of other countries, begins contemplating war with the U.S., due to the worsening worldwide effects of American mismanagement of the environment.
While spending their spring break on the Moon, Titus and his thrill-seeking teenaged friends meet Violet Durn, whose critically questioning attitude is completely new to the others. While at a club, a man from an anti-feed organization hacks all of their feeds. They wake up in a hospital to find, for the first time in most of their lives, that their feeds are unavailable: partially deactivated while under repair. During their recovery, Violet and Titus begin a romantic relationship. Eventually, their feeds are repaired enough for them to return to Earth; however, Violet's feed is not completely fixed.
One day, Violet reveals her idea of resisting the feed to Titus. She plans to show interest in a wide and random assortment of products to prevent the corporations that control the feed from developing a reliable consumer profile of her. The two go to the mall and create wild consumer profiles. Later, Violet realizes that someone has been accessing her personal information through her dreams; this soon becomes a normal occurrence for many feed users. Violet calls FeedTech customer service, but receives no help. Later, Violet tells Titus that her feed has been severely malfunctioning, and she may even die, having had the feed installed later in life (and so with greater accompanying risk). Due to her deteriorating feed, various parts of Violet's body are shutting down. Throughout the novel, there is also a presence of lesions appearing on the characters' bodies. At first it is something they hide, but eventually the lesions turn into a trend. Violet, disgusted with this latest fashion, declares that everyone has become the feed. After this outburst, she collapses and is taken to the hospital.
As a side effect of the malfunction, Violet loses memories of the year before she got the feed installed. To avoid losing more memories, she makes large virtual records of things she can remember. She sends them to Titus for safekeeping, but, not knowing how to emotionally handle this burden, Titus deletes them. Violet's body parts continue shutting down. She and her father cannot afford repairs, so they petition FeedTech for assistance.
Meanwhile, an environmental disaster affecting Mexico causes the Global Alliance to prepare to go to war with the United States. Titus drives to Violet's house. He falls asleep shortly after arriving, but, while he sleeps, Violet shares her bad news with Titus in the form of a dream: FeedTech has decided not to help Violet because of her bizarre and unreliable customer profile. That weekend, Violet comes to Titus's house to ask him to go with her to the mountains. He is reluctant at first, but ultimately agrees. They begin fighting, however, and break up. On the way home, Violet's arm stops working and when she arrives home her leg fails as well. Titus drives away. The next day, Violet apologizes to Titus via feed, but Titus does not answer.
Several months later, Titus receives a message from Violet's father saying that Violet wanted Titus to know when it was "all over." He informs him that the time has come. Titus goes to Violet's house, where she lies in a coma, barely still alive. Her father blames Titus and shows him memories of parts of her body and brain shutting down and the pain she experienced. He then sarcastically tells Titus to be with "the Eloi." Titus asks what that means, but Violet's father refuses to answer, telling him to look it up. They fight, and Titus goes home. In an act of grief, he sits on his floor naked and orders the same pair of jeans continuously over the feed until he is entirely out of credit.
Two days later, Titus goes to visit Violet again. He tells her any stories he can find in the information available through his feed. Finally, he tells her the story of their relationship in the form of a movie trailer. The book ends with Violet's life systems becoming progressively weaker, and the feed ironically repeating the advertising slogan "Everything Must Go" in progressively smaller font.