This novel opens with an introductory section which explains the fukú -- "generally a curse or a doom of some kind; specifically the Curse and the Doom of the New World," and the zafa—a counterspell to the fukú. The narrator of the book, unknown to the reader at this point, explains that the story he is about to tell is his own form of a zafa.
Part I of the book contains an introductory section, as well as the first four chapters of the story, and runs for over half the novel's length.
Chapter one: Ghetto Nerd at the End of the World (1974–1987)
This chapter introduces the reader to the titular character Oscar de León. Oscar comes from a Dominican family, and is therefore expected to be successful with girls. However, Oscar is more successful with science fiction, cartoons, reading, and role-playing games.
This chapter explains Oscar's history as a child through high school, focusing on his inability to find love.
When he was seven, Oscar had a week-long relationship with two girls at the same time, Maritza Chacón and Olga Polanco. When Maritza gives Oscar an ultimatum, he breaks up with Olga, only to be quickly dumped by Maritza. The narrator mentions that this event will cause all three of them to be unlucky in love.
In high school, Oscar is an outcast. He is very overweight and his fascination with "the Genres" causes him to be teased. When his two friends Al and Miggs both find girlfriends and do not involve Oscar (or try to help Oscar find a girlfriend), Oscar quickly stops spending time with them.
During his senior year of high school Oscar takes an SAT review course. While there he sees a girl, named Ana Obregón, reading Tropic of Cancer. Impressed by her literariness he introduces himself and shortly begins to spend a lot of time with her. Oscar shortly falls in love with Ana. When her ex-boyfriend Manny returns from the Army, Ana stops spending time with Oscar. It is around this time that Oscar begins to start writing heavily, science fiction or fantasy stories, mostly centered on the end of the world.
When Oscar discovers that Manny has been physically abusing Ana, Oscar takes his uncle's gun and stands outside of Manny's apartment, but Manny never returns that night.
The chapter ends with Oscar revealing his love to Ana, Ana rejecting him, and Oscar deciding to go to college at Rutgers.
Chapter two: Wildwood (1982–1985)
The narrative changes to the first person, ostensibly from the point of view of Lola, Oscar's sister. Díaz commented in a talk given on September 20, 2012 that this change in narrative style is meant to be understood as Lola's story dictated the lens of the narrator, Yunior, which explains the temporary second person at the outset. It explores the distant and often verbally abusive relationship that Lola has with her Old World Dominican mother, and Lola's resulting rebellion.
It opens with Yunior telling, in the second person (after a few pages changing to first person "Lola"), the story of how Lola found out her mother had breast cancer. It then proceeds to explore the negative relationship that Lola had with her mother. This poor relationship causes Lola to run away from home to live with her boyfriend and his father on the Jersey Shore. After a bit of time, Lola finds herself again unhappy and calls home. She talks with Oscar and convinces him to bring money and meet Lola at a coffee shop. When they meet up, Lola discovers that Oscar told their mother about the meeting.
In an effort to run away from the coffee shop and from her mother, Lola accidentally knocks her cancer-ridden mother over. When Lola turns around to make sure her mother is okay, her mother grabs Lola by the hand, revealing that she was faking crying in an effort to get Lola to come back.
As a result of her running away, Lola is sent to live with her grandmother, La Inca, in the Dominican Republic.
Chapter three: The Three Heartbreaks of Belicia Cabral (1955–1962)
This chapter introduces the reader to the history of Oscar and Lola's mother, whose full name is revealed to be Hypatía Belicia Cabral, though she is usually referred to simply as Beli.
It is revealed that Beli's family died when she was one, with rumors that Trujillo was responsible. She was raised by a series of abusive foster families until her father's cousin, La Inca, rescues her from such a life. La Inca repeatedly tells Beli that her father was a doctor, and that her mother was a nurse as a way to remind Beli of her heritage. La Inca brings Beli back to her hometown of Baní, where La Inca runs a bakery.
At the age of 13, Beli lands a scholarship at El Redentor, one of the best schools in Baní. There, she falls in love with a light-skinned boy named Jack Pujols, and spends a lot of her time trying to earn his affection, to no avail. Because she is poor and dark-skinned, Beli is often made fun of, and is a social outcast. However, during the summer of sophomore year, Beli quickly develops into a full grown and well endowed woman, and the book describes how Beli becomes very popular with men of all ages.
With her new body, Beli is finally able to catch the attention of Jack Pujols and loses her virginity to him. However, when they are discovered in a closet together, Beli is kicked out of school. Instead of transferring to a different school, however, she earns a job at a restaurant run by two Chinese-Mexican immigrant brothers, Juan and José, where she works as a waitress.
After a time, Beli goes to a club with another waitress named Constantina. There, she meets a gangster, and the two of them form a relationship. After a while, Beli is fired from her job. Although the Gangster's authority quickly gets her her job back, she feels it is not the same and resigns. Eventually, Beli becomes pregnant with the Gangster's child. It is then revealed that the gangster is in fact married to one of Trujillo's sisters, "known affectionately as La Fea" (The Ugly). When La Fea discovers that Beli is pregnant with her husband's child, she has two large cops resembling Elvis, with pompadour hairstyles, kidnap Beli, with plans to take her to have a forced abortion. As she is being led to the car, she sees a third cop who does not have a face. Before the cops can drive away, Beli spots her former employers, Juan and José, as well as her former coworkers and calls for help. They come to her rescue and Beli manages to get back to her old home. However, she is tricked into thinking the Gangster is outside in his car, and runs out to meet him, only to run into the same cops from before. The two cops physically beat Beli and leave her close to death, and continue to do so in the cane field. Her fetus dies due to the injuries.
When she discovers that Beli has been taken, La Inca begins to pray very intensely, and in short order, a small but intense prayer group forms around La Inca.
Back in the cane field, after she has been left for dead, a mongoose with golden eyes appears and leads Beli out of the cane, telling her that she will have two children. As Beli returns to the road, she is picked up by a group of traveling musicians. Thanks to La Inca's connections in the medical community, Beli is nursed back to health.
After Beli returns to La Inca's care, it quickly becomes apparent that Beli will not be safe in the Dominican Republic under Trujillo, and so she is sent to live in New York.
Chapter four: Sentimental Education (1988–1992)
This chapter explores Oscar's time at Rutgers, and introduces the narrator, Yunior, who was Oscar's roommate and Lola's boyfriend. Yunior is a big guy, with an even bigger heart. The narrator begins to tell his own story, saying “it” (his involvement with the de Leons) started when he was jumped in New Brunswick on the way home from a club. Lola was the only one who came and took care of him when he was recovering. He admits he cared about Lola even though he thinks he is not supposed to care about anything, and despite the fact that she is not the kind of girl he usually goes for because she is tall with no breasts and huge hips and a butt. Yunior (the name of the narrator is first revealed on p. 169) describes his first kiss with Lola when she asks him to drive her home.
Promising to keep an eye on Oscar while Lola is abroad, Yunior rooms with him the next year in the dorm called Demarest. Lola is as surprised as Yunior is. Yunior has always hated Demarest because it is full of artists, freaks, and losers. Oscar and Yunior get a room specified in the “writing” section. Yunior rooms with Oscar partially because of Lola but also because he would have had to room off campus otherwise and he could not afford it. When Yunior moves in, Oscar tells him he is cursed, but Yunior is not fazed by it. In retrospect, he thinks he probably should have run the other way. Yunior states he has never met a Dominican like Oscar. Oscar is a nerd who writes fifteen to twenty pages a day, and puts signs on their door in fantasy languages from his books. When Yunior comes home at night, he often finds Oscar watching Akira, a Japanese post-apocalyptic film, or role-playing. Yunior admits that Oscar is a considerate roommate, and Yunior does his part to return the favor by cooking dinner and reading some of Oscar’s writing. Yunior tries to give advice to Oscar on how to get girls, but he also believes that Oscar is too nerdy and too fat to get a girl. In addition, Oscar does not want to change. When Yunior’s girlfriend Suriyan dumps him for sleeping with a girl named Awilda, Yunior makes Oscar his project. He takes him running every day. After a while, Oscar quits. Yunior gets angry—Oscar resists, and Yunior pushes him. Lola calls from abroad (in Spain) and they fight—she tells him never to speak to her again. Oscar tried to apologize to Yunior but Yunior did not apologize back and remained cool towards Oscar. Yunior describes how his friends taunt Oscar “Tú no eres nada de dominicano” (You are not one bit Dominican) to which Oscar would protest that he is. On Halloween, Oscar dresses up as Doctor Who, from the TV show; Yunior thought he looked like “that fat homo” Oscar Wilde, their friend Melvin heard “Oscar Wao” and that’s how Oscar got his nickname. Oscar falls in love with a beautiful crazy Puerto Rican goth girl named Jenni Muñoz, also known as La Jablesse. She once turned Yunior down, and he is still a little put off by it. Oscar and Jenni become friends and started to hang out, much to Yunior’s surprise. Yunior admits he reads Oscar’s journal to find out what they talk about, which is mostly poetry and literature. Oscar starts jogging again and making more of an effort to look good. Then Jenni gets a boyfriend and stops hanging out with Oscar. Oscar is depressed and stops writing. Yunior calls Lola because he is worried. Two weeks later Oscar walks in on her and her new boyfriend naked. Oscar freaks out, insults her, and rips posters off her walls. Yunior stops him, but from then on Oscar is thought of as a psycho, and that is how that school year ends. The last night rooming together, they get drunk, and Yunior leaves. Oscar continues to drink and walks onto a train bridge in New Brunswick. When the train is coming, Oscar sees the Golden Mongoose, they look into each other’s eyes, and then it is gone. Oscar has left a suicide note for Yunior, Lola, Beli and Jenni. He jumps off the bridge and lands on the median and lives. Yunior refers to this period as the Fall. Beli, Yunior, and Lola visit Oscar at the hospital. Lola and her mother are fighting. Oscar tells Yunior he believes the curse made him do it, and Yunior does not believe him. Lola and Yunior have a brief conversation about whether or not Oscar should live in Demarest again, and Yunior leaves without fulfilling his desire to kiss Lola. The next year at school Oscar showed up at Yunior’s dorm and they have a short conversation updating each other on their lives. Oscar visits Yunior occasionally but Yunior never visits him. During winter finals, Yunior runs into Lola on the bus and asks her on a date. She accepts reluctantly. They start a relationship and Yunior promises never to lie to Lola. In the spring, Yunior moves back into Demarest with Oscar. Yunior again admits to reading Oscar’s journal, reporting that the fall after the Fall was dark for Oscar. He would take midnight drives in his mother’s car, sometimes almost falling asleep at the wheel, and then at the last minute waking up.
Part II of the book contains an introductory section, as well as chapters Five and Six of the story.
Chapter five: Poor Abelard (1944–1946)
This chapter is the story of Abelard, Belicia's father (Oscar and Lola's grandfather), and the "Bad Thing he said about Trujillo," which causes his family to be torn apart leaving most family members dead. The dictator, Trujillo, known for his sexual desire for young girls, whose families cannot protect them, learns that Abelard's oldest daughter, Jaquelyn, has become a beautiful young teenager. As a father Abelard does not want to give his daughter to Trujillo, as so many other fathers had been forced to do, and does not bring her to the event it had been demanded she come to. Some four weeks later Abelard is arrested for supposedly making a joke that there were no bodies in the trunk of his car. As Trujillo's henchmen disposed of opponents this way he was accused of slandering the dictator. After his arrest and torture his wife learns she is pregnant with what turns out to be her third daughter, Belicia. Two months after the baby's birth she is killed by an army truck in a probable suicide. Her two older daughters die under suspicious circumstance and the baby is taken to be a criada, a child slave. Beli is given over to the care of a foster family, which treats the young child abhorrently. Mistreated and bearing the scars of the hot oil thrown on her back she is rescued at the age of nine by her father's cousin, La Inca, whom she comes to regard as her mother.
Chapter six: Land of the Lost (1992–1995)
This chapter is about the post-college life of Oscar, and the time he spends in the Dominican Republic. He falls in love with an older prostitute named Ybón Pimentel. This results in Oscar being severely beaten, reflecting the same situation of his mother. The golden mongoose, which saved his mother's life, returns to save Oscar's life. Oscar returns to the United States.
Part III of the book contains chapters Seven and Eight, an unnamed section, and the novel's epilogue, "The Final Letter." Part III contains an introductory section where Oscar visits and lies to Yunior about his plans for the future. They also discuss Yunior's relationship with Lola.
Chapter seven: The Final Voyage
Oscar returns to the Dominican Republic to write and to attempt to be with Ybón. His attempts take place over twenty-seven days in which he writes numerous letters to Ybón and shakes off any attempts from family or friends, including Lola, Yunior, La Inca, and Clives, to forget Ybón. Ybón herself resists Oscar for fear of the Capitan, but Oscar is persistent and waves off his family's fears as misunderstanding of their love.
Oscar is captured by the Capitan's friends, whom Yunior calls Gorilla Grodd and Solomon Grundy, and they drive Oscar (and Clives) again to the cane field. Oscar reiterates the power of love and indicates that death would turn him into a "hero, an avenger. Because anything you can dream... you can be." They then shoot Oscar, but his speech suggests that he is fulfilling his lifelong dream of becoming something worth writing about. The chapter ends with the word "Oscar" interrupted by a dash. It is unclear if this is interrupted narration for Yunior or a direct address to Oscar.
Chapter eight: The End of the Story
The narrator reveals the eventual fates of the characters. Beli's cancer returns one year after Oscar's death, killing her ten months later. Yunior speculates that she had given up. La Inca moves back to Bani. Lola breaks up with Yunior, asserting herself after having had enough of his cheating. She soon after meets someone in Miami, marries him, and has a baby girl, named Isis. Yunior has dreams of Oscar for ten years while his life deteriorates, until he hits rock bottom, and follows Oscar's request presumably to write this novel. At the time of the novel, Yunior is married in New Jersey (almost faithfully) and teaches composition at Community College. He and Lola still run into each other occasionally. Although he still thinks about her and how he might have saved their relationship, they only ever talk about Oscar.
The Final Letter
This serves as an epilogue to the novel wherein Yunior describes letters he and Lola received from Oscar before he died. Lola was told to expect Oscar’s novel in the mail, which never arrives. Yunior, on the other hand, finds out that Oscar and Ybón did consummate their relationship.