Craig is a 15-year-old boy who struggles with severe clinical depression. He lives in New York City with his mom, dad, and sister (Sarah). He spends a lot of time hanging out with his friend Aaron and Aaron’s girlfriend Nia. Craig is jealous of Aaron because Aaron seems to do well in school without studying and because Craig himself likes Nia. Craig’s depression began shortly after he started attending a new high school with competitive entrance requirements.
After a party one night, Craig and Aaron walk along the Brooklyn Bridge. Craig climbs up to a dangerous place where there’s no guardrail and feels both frightened and exhilarated. He keeps thinking about the bridge and eventually develops a plan to kill himself by jumping off it.
One night, after sleeping in his mom’s bed, Craig makes a plan to go out to the Brooklyn Bridge. As he’s considering how to get there, however, he decides to call a suicide hotline instead. The person on the hotline advises him to go to an emergency room, and this is how Craig ends up committed to a psychiatric hospital.
Craig learns from people like the day-time director at the hospital, Smitty, that a psychiatric hospital isn’t exactly what he expected. He is not a prisoner and can get a pass to leave, if he needs to, and there is a smoking lounge that several of the patients use, although Craig himself doesn’t smoke cigarettes.
Although Craig has low self-esteem and fears people don’t like him, he quickly begins to meet other patients in the psychiatric hospital like Humble and Bobby who have very different life stories but who bond with Craig over their shared mental health struggles. Craig takes a particular interest in Noelle, a girl his age who initially doesn’t speak much, preferring instead to communicate with notes.
Craig learns to better express himself and to understand his depression through the activities at the psychiatric hospital, particularly drawing and music. During an art class, he begins drawing maps that resemble the human brain, which impress many of the other patients. These brain maps become Craig’s signature and help him to understand the power of art and self-expression.
One day, Nia visits the psychiatric hospital and tells Craig she’s broken up with Aaron. She herself suffers from depression and seems to initially be seeking out someone like Craig who understands her. As Nia and Craig start kissing, however, Craig realizes that Nia finds something exotic about the extent of Craig’s depression. They get interrupted and Nia leaves, with Craig now realizing that his ideal image of Nia was partly an illusion.
Noelle saw Craig and Nia kissing, so Craig goes to her and apologizes, saying that she is the one he really likes. Craig and Noelle have gotten closer by meeting occasionally to play a game where they each ask the other one questions. Noelle eventually forgives Craig.
Before long, Craig starts preparing to leave the psychiatric hospital. During a discussion with his therapist, Dr. Minerva, Craig comes to the realization that he doesn’t have to stay at his competitive high school and could instead transfer to an art school where he might fit in better. Later, during a group movie night, Craig’s room is empty, and so he and Noelle sneak over there to make out. Craig feels that in spite of all his mental health struggles up until that point, at that moment, he’s really happy.
Craig’s parents come to the hospital on the day of Craig’s scheduled discharge. Craig says goodbye to all his new friends, and he promises to keep in touch with some of them.
On the way home, Craig asks his family if he can just walk alone for a minute. Craig walks down the streets of New York City thinking about all the things he still wants to do with his life and how now he’s going to dedicate himself to living his life more fully than he ever did before.
