The book shares the story of Oscar Wao (whose real name is Oscar de León), a Dominican American who never fits in with his communities, as he tries to assert his own identity and find love in the process. Told by Oscar’s college roommate, Yunior, the book also includes flashbacks into the lives of Oscar’s mother and his grandfather, as they suffered during the Trujillo regime in the Dominican Republic and finally came to America. Interweaved throughout, Yunior also tries to explain and understand his own failed relationship with Oscar’s sister, Lola, and the Dominican heritage that binds them all together. Yunior also adds footnotes throughout the book with humorous asides, stories of Dominican history, or quotes from other books that help illuminate Oscar’s life.
The book starts by introducing Yunior, the fictional author of Oscar Wao’s biography, and the curse that has shaped the events of Oscar’s life. Yunior describes Oscar’s childhood as a Dominican American boy in Paterson, New Jersey, and the struggles that Oscar faces as he fails to fit in with the Latino community or get a girlfriend. Oscar pursues girls, but eventually retreats into science fiction, fantasy, and role-playing games. When he and his sister Lola spend summers with their great-aunt in the Dominican Republic (DR), Oscar realizes that he wants to become an author. Back in Paterson, Oscar becomes obsessed with a girl named Ana, threatening her abusive boyfriend with a gun. Lola calms him down, and Oscar decides to wait until college to find a new love.
The novel then switches to Lola’s perspective. Lola’s strained relationship with her mother causes her to act out. The situation worsens when her mother is diagnosed with breast cancer and Lola decides to run away with her latest boyfriend. However, living in a trailer with her boyfriend and his father is not the escape from her mother’s toxicity and illness that Lola imagined. She gets back in touch with Oscar, planning to meet him at a café, but their mother catches her there. Lola is sent to the DR to attend school and live with her great-aunt. She adapts to life as a real “dominicana” and starts to come to terms with her tangled family history.
From there, the novel goes further back in time to describe the adolescence of Lola and Oscar’s mother, Beli. Beli lives with her aunt, La Inca, in Baní, a fairly poor neighborhood of Santo Domingo. With her dark skin and headstrong manner, Beli does not fit in at her prestigious private school. As she grows into a great and “terrible beauty,” boy-crazy Beli begins to catch the eye of the wrong type of men. Her greatest love, known as the Gangster, works for the dictator Trujillo, and Beli soon finds herself in way over her head when she gets pregnant. The gangster reveals that he is actually married to Trujillo’s sister, and that Beli will have to get rid of the child and disappear. Beli refuses, and the Gangster’s wife has Beli beaten and left for dead. Beli miraculously recovers with the help of a magical mongoose, but loses the baby. She leaves for America in disgrace and meets the future father of Oscar and Lola on the plane to New York.
The novel then comes back to Oscar’s life, during his college years when Yunior himself enters the story. While Oscar studies creative writing at Rutgers University, Yunior becomes his roommate in order to get closer to Lola, with whom he is infatuated. Yunior attempts to reform Oscar in the image of the Dominican American “player,” but Oscar resists this transformation. Yunior and his friends give Oscar the nickname “Oscar Wao” and tease him mercilessly. Disregarding these barbs, Oscar strikes up an unlikely friendship with a beautiful girl on campus, but is shattered when she continues to see other guys. Oscar falls into a deep depression and attempts suicide on the last day of the school year. He survives, and Yunior tries to help Lola pick up the pieces of her life, but mostly struggles to maintain the large network of girls he is sleeping with. Still, Yunior proves his friendship by coming back to room with Oscar for another year.
The novel returns to Lola’s perspective, as she prepares to come back to the States from her year in Santo Domingo. Though Lola desperately wishes to stay in the Dominican Republic and avoid her overbearing mother a bit longer, the death of a boy she was seeing convinces her to do what is best for her family. She gives all of her savings to the boy’s family and meets her mother at the airport.
Reaching back further in history, the novel brings in Abelard Cabral, Beli’s father and Oscar and Lola’s grandfather. A doctor and a scholar, and heir to one of the more well-off Dominican families, Abelard wants nothing to do with Trujillo. He supports the regime in order to keep his family safe, but runs out of luck when Trujillo decides he wants to seduce Abelard’s beautiful oldest daughter Jacquelyn. Abelard is taken by the Trujillato (Trujillo’s police) and thrown into prison for resisting Trujillo’s request, though rumors say that Abelard’s true crime was writing secret, slanderous books about Trujillo’s connection with the “fukú” curse. Meanwhile, Abelard’s wife gives birth to their third daughter but commits suicide soon after. Abelard remains in prison for the rest of his life. The three Cabral girls are split up and the older two die tragically young. The third daughter, Beli, is sold as a maid to cover family debts. In 1955, La Inca finds her and gives her a new life in Baní.
Back in the 1990s again, Oscar has graduated college but moves back with his mother in Paterson and teaches high school English rather than achieving his dream of being a writer. Depression weighs heavily on him, and his lack of social confidence keeps him more isolated than ever. Three years later, Oscar goes again to visit Santo Domingo and meets Ybón, a prostitute who lives next door to La Inca. Oscar falls hopelessly in love, despite his family’s disapproval. Ybón’s biggest client, the Capitán, starts to take notice of how much time Oscar and Ybón spend together, and he threatens them with violence. Oscar takes no notice and receives a harsh beating when the Capitán sees Ybón and Oscar kiss. Like his mother years before, Oscar survives and goes back to the States to heal.
However, Oscar is not done with Ybón or Santo Domingo. Rather than return to teaching high school, Oscar asks Yunior for money. Yunior gives it to him as a peace offering to Lola, with whom he is fighting again, but does not know that Oscar will use it to go back to Ybón. No one finds out about Oscar’s plan until he is on the plane to the DR.
Oscar stays for a month at La Inca’s house before he sees Ybón again. He writes letters back to the States, but no one can persuade him to give up his obsession with Ybón. Oscar and Ybón finally spend one weekend together, where Oscar loses his virginity and finds true intimacy with her. That peace is cruelly destroyed when the Capitán finds out that Oscar is back and shoots him in a canefield.
The book ends as Yunior, Lola, and Beli mourn Oscar. Yunior receives more letters that Oscar sent back from the DR before his death, and starts to compile Oscar’s letters into a book. Lola marries a Cuban man and moves to Miami. She has a daughter, Isis, and keeps in contact with Yunior in honor of Oscar’s memory. Yunior researches Oscar’s life and family, revealing that the entire book was written so that Yunior could piece together his own thoughts about the Dominican American experience. Yunior decides to give the book to Lola’s daughter once she is old enough to wonder about her uncle and her own Dominican heritage.