The novel opens as Julia Reyes, the story’s young narrator and protagonist, attends the funeral of her older sister. Olga Reyes was killed suddenly after she was struck by a bus while crossing the street. Julia reflects on Olga’s demure nature, and she calls Olga the “perfect Mexican daughter.” Olga's personality is a strong contrast to Julia's bold, independent nature. Julia, a first-generation Mexican immigrant living in an impoverished neighborhood in Chicago, is left alone at home with Amá (her mother) and Apá (her father). Following Olga's death, Amá is enthusiastic about throwing Julia a quinceañera, a traditional Mexican ceremony for a girl’s fifteenth birthday. Julia understands that this is her mother's forced attempt to cope with her own grief.
Julia suspects that Olga had a secret life. Against her mother's wishes, she enters her sister's room in hopes of finding clues. After snooping around in Olga's closet, Julia finds lingerie and a hotel room key. She frantically searches for more clues, but she falls asleep mid-pursuit. When Amá finds Julia in the morning, she chastises her daughter and grounds her. Julia attempts to visit the Continental Hotel to find out more, but the concierge is unable to help her. Julia also tries to consult Angie, Olga's best friend, though Angie is hesitant to open up to her. Julia confides in Lorena, her "unlikely" best friend, though their friendship becomes threatened when Lorena befriends Juanga.
Julia has a hard time in school, and she is often chastised for rejecting authority and talking back to teachers. Although school is difficult for her, she is a voracious reader and excels in her English classes. Julia hopes one day to move to New York and become a writer, and one of her teachers, Mr. Ingman, acknowledges her potential and supports her immensely. Mr. Ingman's encouragement is especially important, since Julia has deep bouts of depression and anxiety that profoundly affect her self-esteem. Tensions are magnified at home, where Julia's relationship with her mother becomes even more fraught. Amá blames Julia for Olga's death, which weighs heavily on Julia. One day, Julia sneaks out of the house and goes to a bookshop. There, she meets Connor, and the two begin to go on dates. Julia's relationship with Connor becomes a silver lining in Julia's otherwise tumultuous life.
One day, Julia walks into the living room to see Amá crying over boxes of clothes. She has gone into Julia’s closet in order to donate old belongings, but she has also recovered the items that Julia has taken from Olga. Amá is convinced that the hotel key, lingerie, and box of condoms all belong to Julia, and she threatens to send Julia away to live in Mexico. Frustrated by the “explicit content” of the recovered belongings, Amá grounds Julia yet again, and this time she’s unable to see Connor. Although she speaks to Connor on the phone daily, he grows frustrated at his inability to support Julia through her depression. One day, Julia decides to go to Millennium Park after school. While there, she grows dizzy and lightheaded. In the next scene, the reader learns that Julia has attempted to take her own life, and she is now in a psychiatric unit. She is sent to an outpatient therapy program for one week, led by a psychiatrist named Dr. Cooke.
Following her time in the psychiatric program, Amá and Apá send Julia to visit her grandmother in Mexico. Although initially Julia does not want to make the trip, it turns out to be a fruitful and pleasant vacation. Julia is able to reconnect with her family, and she even discovers that Apá was once a talented artist. Julia also learns that Amá was violently assaulted when she crossed the border, which paints a different picture of her hardened mother. In Mexico, Julia also witnesses a shooting, which informs her of the violence and poverty that continues to dominate the region.
Upon her return from Mexico, Julia's relationship with Amá takes a turn for the better. Additionally, Julia discovers that Olga was having an affair with an older doctor who worked in her office named Dr. Castillo. Julia also discovers that at the time of her death, Olga was twelve weeks pregnant with Dr. Castillo's baby. Julia decides to confront Dr. Castillo, and she finds that he is much more pained and heartbroken than she had imagined he would be. As the spring progresses, Julia grows excited about her college acceptance laters. She discovers she has been accepted to New York University on a full scholarship, and she can finally realize her dream of moving to New York in the fall. She also reconnects with Connor, and the two share their summer together. In the story's final scene, Julia lands in New York. She holds the ultrasound of Olga’s baby in her hands and thinks about the trials and tribulations of the past two years.
