Craig Gilner, the narrator, is 16 years old and lives with his family in a middle-class Brooklyn neighborhood. He attends the prestigious Executive Pre-Professional High School, having studied arduously to win admission. Once admitted, however, he becomes overwhelmed by the school's intense academic pressure. He has a longstanding crush on Nia, who is dating his best friend, Aaron. He feels alienated and unable to fit in.
His stress eventually manifests itself in an eating disorder, affects sleep habits, and suicidal thoughts. He takes a stand and goes to a psychiatrist who prescribes him Zoloft. He is elated for a brief period, and believes he is cured (what he calls "The Fake Shift")—so he decides to throw away the medicine. Consequently, his depression builds until, unable to fend off his suicidal ideation, he calls 1-800-SUICIDE and is admitted to a nearby psychiatric hospital. He is initially taken aback and feels he doesn't belong in a loony bin. With the adolescent floor of the hospital being full, Craig is sent to stay on the adult floor. He meets many other patients, some friendly, others reclusive or delusional, and is supported and encouraged by his family and school principal once they learn of his hospitalization.
He is apprehensive about going back to school and talks to his psychiatrist, Dr. Minerva, about this. Craig meets a female patient, Noelle, who coped with a history of abuse by cutting her face with scissors. In isolation from the outside world, and with help from Noelle, Craig confronts the sources of his anxiety and regains his health.
During his recovery, Craig experiments with art, specifically stylized human figure maps, and discovers he has a great deal of natural talent and ability. He realizes his art makes him feel good and wishes to pursue it. Once Craig has recovered, his counselor suggests he transfer to an art school, a thought that excites him. However, he is scared of telling his father the same, who considers people at art school "messed up". He returns home at the novel's end, with a new energy to live life. He begins to appreciate the little things that make him happy.
