August introduces himself to the reader. He's ten years old, and though he feels normal, he wishes he had a "normal" face. He declines to describe what his face looks like, insisting that it's probably worse than whatever the reader is imagining. August has been homeschooled his entire life because he's had so many surgeries. However, one day in the spring, August overhears Mom and Dad talking about sending August to middle school. August is upset and doesn't want to go, but he agrees to try. When August and Mom tour Beecher Prep, the principal, Mr. Tushman, introduces August to three students. August is terrified—he hates meeting kids his own age because they often are purposefully mean. Mr. Tushman introduces August to Jack, Charlotte, and Julian and then sends the kids to look around the school. Charlotte and Jack are nice, but Julian is rude and tries to make August feel bad and unwelcome. After August and Mom get home, August tells her about some of Julian’s mean comments. She's horrified and doesn't want August to go to school, but August and Dad insist that he should still try.
Mom, Dad, and August's older sister, Via, walk him to school on his first day. Jack sits next to August in all their classes. Julian is still mean to August, though the teachers don't notice. At lunch, August sits alone until a girl named Summer sits down with him. After school, August tells Mom that his day was okay, which surprises her. August struggles in school all through September, especially when he realizes that kids are scared to touch him. However, he and Jack become good friends.
For Halloween, August decides to go as Boba Fett from Star Wars. Halloween is his favorite holiday because he gets to wear a mask and feel like a normal kid. On Halloween morning, however, he decides to wear last year’s Bleeding Scream costume to school instead. August feels amazing in his costume until he gets to homeroom. There, he overhears Jack telling Julian that if he were August, he'd kill himself. Since August’s classmates are still anticipating him arriving as Boba Fett, no one knows that he is the one in the Bleeding Scream costume, listening to every word of the mean conversation. August runs out crying, goes home, and skips school the next day.
Via takes over the narration and explains that in her family, August is the center of the universe. She doesn't ask for much from her parents because she knows that August needs the attention more. Via has always been protective of August, but she didn't realize how much she wants to be normal until a month-long visit with Grans a few years ago. On that visit, Grans told Via that she was looking out for her, since August has enough angels looking out for him. Grans died two months later.
Via says that she loved middle school because she had her two best friends, Miranda and Ella, and not many kids knew about August. Miranda was always nice to August and even bought him his space helmet that he wore constantly until it disappeared. Now that the girls are in high school, Miranda is very different. She's changed her hair and clothes and treats Via like she's not a real friend. On the first day of school, Via is so hurt she takes the subway home alone rather than let Miranda's mom drive her. Via eventually makes some new friends and develops a crush on a boy named Justin.
Grans died the night before Halloween, so Via feels very sad on Halloween morning. Dad is in a bad mood and makes Via cry, so Mom suggests that she and Via stay home. However, their morning at home has barely begun when Mom gets a call from Beecher Prep that August is sick and needs to be picked up. Via is shocked later when August insists he's too sick to go trick-or-treating. Finally, he confides in her about what Jack said. Over the weekend, Via convinces August that he needs to go back to school.
Summer begins to narrate and says that she sat with August on the first day of school because she felt bad for him, but she discovered quickly that he's a lot of fun. He's still interested in playing games like foursquare instead of "hanging out" and talking about crushes. After a few weeks, a classmate tells Summer about a game the class is playing called the Plague, which states that kids have thirty seconds to wash their hands after touching August or they catch the Plague. This is why nobody will play with August and Summer.
Savanna, the most popular girl in school, invites Summer to a Halloween party. At the party, Summer understands immediately that Savanna invited her to intimidate her and try to get her to stop spending time with August, so Summer calls her mom to come pick her up. At lunch on Monday, August tells her what Jack said on Halloween but swears her to secrecy. Later that month, Jack approaches Summer and asks why August is ignoring him. Summer just tells him, "Bleeding Scream."
Jack jumps back to the month of August when his mom got a call from Mr. Tushman, asking if Jack would be willing to show August around the school. Jack refused, which made Jack's mom very mad. Jack recalls the first time he saw August—he jumped and made a surprised noise. His babysitter, Veronica, whisked Jack and his little brother, Jamie, away before they could make the situation worse. She told Jack that he doesn't need to be actively mean to hurt someone's feelings. When he hears Jamie being mean to August, Jack thinks about what Veronica told him and changes his mind about meeting August. After a few weeks of school, Jack realizes that August is actually really cool: he lets Jack cheat off his homework, and he's funny. He's perplexed when August starts icing him out after Halloween, and has no idea what Summer's "Bleeding Scream" comment means. Right before winter break, however, Jack realizes what she meant. He feels sick that August heard him saying such mean things, when he only wanted to impress Julian.
When Julian taunts Jack a little later, Jack punches him. Mr. Tushman suspends Jack. Julian's mom writes Mr. Tushman and asks that August not be allowed at school, as she thinks it's too much to ask to ask "regular" kids to be nice to him. Mr. Tushman refutes this. Jack also apologizes to August over text, and August forgives him. They return to school in January to discover that none of their classmates will talk to them. Charlotte tells Jack that Julian has begun a war, which mostly entails ignoring Jack until he decides to drop August.
The narration switches to Justin, Via's boyfriend. He meets August the first time he goes over to Via's house, and he tries not to be shocked by August. Mr. Davenport, the theater director, casts Justin in the leading role of Our Town, the spring show, and Miranda gets the female lead. One afternoon, Mom asks Justin to walk Jack to the bus. Justin thinks that Jack is too small to be running around by himself, and vows to be more protective when he has kids one day. He watches Julian, Miles, and Henry bully Jack, and after Jack gets on the bus, he tells them to leave Jack alone. The next day at rehearsal, Justin learns that Miranda and Via used to be good friends. He's shocked, but when he brings it up to Via, she cries and admits that she hasn't told her parents about the play because she doesn't want them to bring August. She loves being at a school where nobody knows about him.
August resumes his narration in February, which is the worst month for the war. Julian leaves mean notes in August's locker, but August refuses to report them. By March, kids start to lose interest, and former bullies like Amos even start standing up to Julian. August gets hearing aids about this time, something that horrified him until he realized how well he could hear with them. After spring break, Mom and Via fight when Mom finds out that Via didn't tell her about Our Town. At dinner, when August asks if they'll all go, Mom tries to tell him it won't be interesting. August realizes they're trying to exclude him and yells at her to not treat him like a baby. He runs to his room and hides until Via bursts in, yelling that he needs to come say goodbye to their dog, Daisy—she's very sick and has to be put down. That night, August watches his family members grieve and then puts himself to bed instead of waiting to be tucked in. A few days later, August sits with Mom and Dad in the audience to see Our Town. They're all shocked when Via, who was cast as an understudy, performs as the female lead instead of Miranda.
Miranda explains that at summer camp, she started talking about August as though he was her own brother, which boosted her popularity immensely. She also got a makeover at camp and looked like a popular girl by the time school started. She and Via stopped being friends, but she signed up for theater to be in the same class with her. On the play’s opening night, Miranda's parents don’t show up, so she feigns illness and allows Via to perform since her whole family is there. Afterwards, she finds August and his parents, and they invite her to dinner. She feels happier than she has in a long time.
August explains that all the fifth graders go on a nature retreat for two nights at the end of the year. August loves the first two days of the nature retreat, especially because Julian decided not to attend. On the final night, Beecher Prep joins two other schools at an outdoor movie. At one point, Jack and August run into a group of bullies from another school. The bullies taunt August and don't even seem deterred when Amos, Miles, and Henry try to stand up for August and Jack. After a brief but traumatizing fight, Amos, Miles, and Henry lead August and Jack far away to escape. August realizes that he lost his hearing aids in the tussle and cries, but the boys comfort him kindly and then walk him back to the movie.
The next day, after Mom picks August up, he asks her if he'll always have to deal with jerks. She insists that there are more good people than bad in the world. A few days before school gets out, Mr. Tushman calls August to the office to explain that he found the bullies, though August refuses to press charges.
The day of the fifth grade graduation ceremony. On the way there, Dad admits that he threw away August's space helmet. August is livid, but soon forgives his dad. At the ceremony, Mr. Tushman gives a speech about the importance of kindness and then presents awards. August receives the Henry Ward Beecher Medal for bravery and kindness and revels in his standing ovation. Afterwards, he lets his parents and his friends' parents take photos of him and all his classmates. On the walk home, August thanks Mom for making him go to school.