Fifteen-year-old Ari wakes up on the first day of summer vacation feeling miserable. In order to escape Mom’s church friends, Ari goes to the pool. On the walk there, he thinks about how Vietnam changed Dad, and how Dad won’t talk about Vietnam or Ari’s older brother, Bernardo, who’s in prison. Ari doesn’t know what crime Bernardo committed. At the pool, Ari doesn’t know how to swim and hates the sexist lifeguards. A skinny and squeaky boy named Dante offers to teach Ari to swim. They become friends instantly. After a few swimming lessons, Dante introduces Ari to his parents. Mr. Quintana is happy, open, and inquisitive, but Dante says that Mrs. Quintana is “inscrutable.” Ari doesn’t know what the word means, but he thinks that Dad is inscrutable too. Dante cleans his room while Ari reads poetry, which Ari is surprised to enjoy. A few days later, Dante introduces himself to Mom and Dad, and gives Dad a book of Mexican art. Ari learns that Dad studied art before he went to Vietnam. Ari and Dante discuss that they’re budding intellectuals, and Dante says he’s trying to not be ashamed. Ari tells the reader that he’s ashamed, too, but only Dante knows why.
Ari and Dante discuss Mexican nicknames, and Dante shares that he doesn’t think he’s Mexican enough. Dante spends the summer waging war on shoes, and as an excuse to destroy his, he invents a game in which he and Ari throw their shoes as far as they can in the street. One afternoon, Dante sees three boys shooting birds with BB guns. In a rage, he threatens the boys. Dante cries and Ari helps him bury the bird, feeling horrible because he’s not sad.
The next morning, Ari wakes up with the flu. Dad rocks and comforts him when Ari has bad dreams. As Ari recovers, Dad admits that he has bad dreams, too, and apologizes for being so distant. Dante comes over to draw Ari. It intrigues Ari when Dante refuses to let him look at the sketchpad. That night, Ari has bad dreams about not being able to reach Bernardo and Dante, and others about killing birds. His fever returns and Ari begins to feel older and lonelier than ever. He resurrects his childhood journal and talks with Dante more about whether or not they’re Mexican enough. Following this conversation, Ari and Mom talk a little about Mom’s education and the pain of the war that Dad carries with him everywhere. She tells Ari that someday, he’ll understand. Later, Ari finds an entry in his journal in which he laments that getting older isn’t fun and another about how nobody talks about Bernardo. Feeling afraid, Ari writes that if Dante knew who he really was, Dante wouldn’t like him.
Mom lets Ari visit Dante. The boys sit outside to watch a rainstorm. They discuss that they’re good boys, but they want to be bad. Dante suggests they take a walk and tells Ari that he’s moving to Chicago for a year. Then, he sees an injured bird in the middle of the street. He picks it up as a car comes around the corner. Ari screams for Dante and wakes up in the hospital with casts on both legs and one arm. Ari tries to make jokes, asks for Dante, and asks what happened to the bird. Mom explains that Ari saved Dante and that the car ran over Ari’s legs. Dante arrives and tearfully thanks Ari, but Ari tries to insist that he didn’t save Dante on purpose. Throughout Ari’s hospital stay, he insists constantly that saving Dante was instinct. He hates Mr. and Mrs. Quintana’s gratitude, though he appreciates it when Dante brings him books. Dante also leaves Ari his sketchbook, but Ari throws it across the room in a fit of rage. When Mom reprimands Ari and asks him to talk to her, he says that he’ll talk when she talks about Bernardo. Finally, Ari gets to go home. He watches birds out the windows of the car.
Ari is confined to a wheelchair while his legs heal, which he hates. He feels helpless and sad when Mom bathes him. Ari and Dante discuss the merits of seeing a counselor and one day, Dante asks to give Ari a sponge bath. Ari agrees, but feels angry and cruel when he sees Dante crying. When Ari gets his leg casts changed and his arm cast off, Mom and Dad agree to buy him a pickup truck for his birthday, but this is the only bright spot—Ari feels angry at everyone and everything. He wants to know who he is, and writes in his journal that for his birthday, he wants someone to talk about Bernardo. That night, Dante tells Ari that he loves him. Ari realizes he doesn’t hate anyone and assures Dante that they’ll still be friends when Dante gets back. The night before the Quintanas leave, they have dinner at Ari’s house and Ari and Dante look through Dante’s sketchpad. Ari feels extremely sad.
Ari’s friends at school, Gina and Susie, don’t believe him when he says that he saved a guy named Dante and broke his legs. This delights him. On the second day of school, a pretty girl named Ileana writes her name on Ari’s casts, and Ari is transfixed by her. He gets a red pickup truck for his birthday and sits in it every morning. One night, he dreams that he hits Dante with his truck because he is looking at Ileana. Dante writes several letters per week about parties and experimenting with drugs. Dante has his first kiss with a girl named Emma, and Ari wonders what it’d be like to kiss Ileana. Ari’s bad dreams persist. He decides that he’s going to kiss Ileana and vows to figure out what Bernardo did.
Dante writes about the art he sees at the Art Institute of Chicago as Ari pursues Ileana. When he gets his casts off, he takes a walk and a stray dog follows him home. He names her Legs, and writes to Dante about her and about his driving lessons with Dad. In his journal, Ari writes about all the things he’s doing, including his new job at the Charcoaler. He feels like he’s falling in love with Ileana and begins to realize that he’s not silent like Dad: on the inside, he’s verbal like Dante. Ari finally gets his license and drives out to the desert to celebrate. A while later, when Mom and Dad are at a wedding, Ari buys beer, gets drunk in the driveway, and thinks about Bernardo. Right before Christmas, he discovers a folder labeled with Bernardo’s name. He wants to open it, but also wants Mom to give it to him. For Christmas, Dante gives Ari miniature tennis shoes for his rearview mirror and Ari gives Dante an art book. Surprisingly, Mom lets Ari go to a New Year’s party, where Ileana kisses Ari. Dante writes to Ari about masturbating, which Ari finds embarrassing and disturbing. Ileana breaks things off with Ari—her boyfriend is in a street gang. She gets pregnant and drops out of school.
In a letter, Dante confesses that he’d rather kiss boys than girls, but he’s afraid to tell his dad—he knows he’ll disappoint him. On the last day of school, Gina and Susie take Ari out to the desert so he can drink. The next morning, Ari and Mom argue about whether Ari is a good person and if he’s ever going to stop beating up on himself or stop making jokes about being stereotypically Mexican. Mom insists that Ari is in transition. Dante and his family return to El Paso, and he meets up with Ari while Ari and Legs are running. Ari reunites with the Quintanas, and observes that Mrs. Quintana looks more beautiful than ever. That evening, Ari drives to the Quintanas’ house in his truck and lets Mr. Quintana take it for a spin. While his parents are gone, Dante and Ari lay ground rules for the summer: Dante can’t kiss Ari, and Ari can’t abandon Dante when people tease him for hanging out with a gay guy. They drive out to the desert and there, Dante says that his mom is pregnant. He hopes it’s a boy who likes girls. Dante cries and says that he has to come out to his parents, but he feels like he’s disappointing everyone. A few nights later, Dante suggests they try kissing, in case Ari does like kissing boys. Ari agrees to the kiss, but insists that he doesn’t like it.
The boys ignore each other for a few days. A few weeks later, Ari dwells on Bernardo and invites Dante to get drunk with him. Mom is visiting Aunt Ophelia and when he realizes he’s home alone with Dad, Ari angrily thinks through the conversation he’d like to have with Dad. In it, he accuses Dad of being silent about Bernardo. Dante helps Ari out to the desert and there, Ari collapses and cries. The next day, Ari is enraged to discover that Gina and Susie came across Dante at the drugstore where Dante works and now know about the accident. They make up the next day when they take joints out to the desert and run naked in the rain while their dads bowl. Dante admits that a coworker named Daniel likes him.
Dad wakes Ari up to go to Tucson—Aunt Ophelia had a stroke and is dying. In the car, Dad and Ari talk. Dad says that Ari lived with Ophelia during Bernardo’s trial for nine months because Mom had a breakdown. Dad gets out to cry and Ari stands with him. Ophelia dies before Ari and Dad arrive. None of their extended family attends the funeral and Mom explains that it’s because Ophelia was gay, something that both Mom and Dad say didn’t bother them. Mom agrees to show Ari pictures of Bernardo when they get home.
The morning after Ari and his parents get home, Ari goes to pick up Legs from the Quintanas’ house. Mr. Quintana tells Ari that a group of boys jumped Dante when they found him kissing another boy. Dante is in the hospital, and Mr. Quintana is distraught that Dante never told him about his sexuality. He asks Ari to call him Sam. Ari doesn’t know what to do. He visits Dante, where Sam and Mrs. Quintana affirm that Ari will always be Dante’s friend. Then, Ari tracks down Daniel and one of the boys who beat Dante, Julian. He breaks Julian’s nose. When Ari arrives home covered in blood, he tells his parents why he beat Julian, and says that Dante didn’t run when the boys jumped him. Mom gives Bernardo’s file to Ari. Over the next few days, Dad answers Ari’s questions and Ari visits Dante. Ari tells the Quintanas that he’s not going to pay for Julian’s hospital bill if Julian isn’t going to pay for Dante’s.
Ari tells Dante what happened to Bernardo: when he was 15, he picked up a prostitute who turned out to be a "transvestite" (likely referring to a man who prefers to dress in stereotypically feminine clothing). Enraged, Bernardo killed her and then another man in prison. They discuss Ari’s choice to beat up Julian, and Dante assures Ari that he’s not like Bernardo. Dante also admits that he imagines he’s kissing Ari when he kisses Daniel. A few days later, when Ari tries to visit Dante, he leaves when he learns that Daniel is already there. Ari and Dante argue about this and Ari ignores Dante for a few days. After a few days, Mom talks to Ari about Bernardo and Ari punches the wall. Mom pulls out wine and beer and calls a family meeting. Dad tells Ari about a haunting experience in Vietnam and then tells Ari that he needs to face that he’s in love with Dante. Ari cries and admits that he’s ashamed of his sexuality. Mom tells Ari to not hate himself and Dad reminds Ari that when the boys beat Dante, Dante didn’t run.
Ari calls Dante. They go bowling with Dad and Sam, and then drive out to the desert. There, Ari admits that he lied about their kiss—he did like kissing Dante. They kiss and then look at the stars. Ari wonders how he could’ve ever been ashamed of loving Dante.
