The story opens with the protagonist, nine-year-old Rosaura, arriving at Luciana's birthday party. She confirms that there is a monkey in the kitchen. Rosaura is relieved because her mother had insisted it was nonsense to believe a monkey would be at a birthday party.
The narrative digresses to depict the conversation Rosaura and her mother had earlier. Her mother, Herminia, hesitates to let Rosaura attend a rich person's party, while Rosaura wants nothing more than to go. Herminia reminds Rosaura that Luciana's mother invited Rosaura not because she is Luciana's friend, but because she is the daughter of Luciana's mother's maid. Rosaura refutes this. Herminia is aware of her daughter's high opinion of herself and accuses her daughter of liking to "fart higher than her ass." Rosaura disapproves of her mother's coarse language. She secretly wishes to be rich and live in a large house one day. She wonders if her mother will still love her.
Despite their argument, on the day of the party Rosaura discovers that her mother has starched her formal Christmas dress. At the party, Rosaura is thrilled to confirm the monkey's presence in the kitchen. She is proud when Señora Ines compliments her ability to carry a jug of orange juice without spilling a drop. Rosaura is the only child allowed into the kitchen to help serve the guests: Señora Ines says the others are too boisterous.
Luciana's cousin interrogates Rosaura about who she is and how she knows Luciana. Rosaura says they do homework together, and that she is "the daughter of the employee," a phrase her mother told her to use. Before the cousin can probe further, Ines intervenes and asks Rosaura to help serve hot dogs.
Rosaura finds that she has never been so happy. She wins the sack race and all the boys want her to be on their team for charades. Ines asks Rosaura to help serve the slices of cake, and Rosaura feels a queen's power of life and death over her subjects as she decides who deserves the most generous and the most measly slices. During the magic show, Rosaura holds the small monkey in her arms while the magician makes it disappear. The magician thanks her, referring to her as his little countess.
When her mother comes to take her home, Rosaura is filled with emotions and impressions from the day. She is thrilled to report what the magician said, for which Herminia playfully teases her daughter. Before Rosaura and her mother leave, Señora Ines asks Rosaura to wait. Rosaura's mother grows worried, but Rosaura assumes she is about to receive a parting gift like the other children have received. She watches Ines fetch a blue bag of yo-yos for boys and a pink bag of bracelets for girls.
When Ines tells Herminia what a marvelous daughter she has, Rosaura believes her excellent behavior might merit two gifts. However, Ines instead withdraws two bills from her purse and holds them out to Rosaura, saying she truly deserves the money for all the help she provided. The story ends on the image of Rosaura and her mother standing with their arms tight to their sides, insulted by the gesture, while Ines remains still, unable to withdraw the money for fear of shattering the delicate balance that keeps her in a position of power over the working-class women.