The narrator quotes letters from the Marquesa de Montemayor praising Uncle Pio’s conversation while lamenting his disreputable lifestyle. Uncle Pio serves Camila Perichole as maid, teacher, banker, and more—doing all her reading and writing, as she is illiterate—and regards her as the greatest actress in the Spanish-speaking world.

Uncle Pio was born out of wedlock into a Castilian family; he ran away to Madrid at 10 and survived by his wits, working as a circus trainer, government agent, and spy for competing political factions. A reluctance to commit to anything prevented him from accumulating wealth.

His life has three aims: maintaining independence while possessing secret knowledge; staying near beautiful women, whom he serves devotedly; and remaining close to Spanish literature, especially theater. After a quarrel forces him to Peru, Uncle Pio continues his varied schemes and is employed by the viceroy, Don Andrés. He discovers 12-year-old Micaela Villegas singing in cafés and trains her into Camila Perichole, a performer of extraordinary grace. They develop deep but nonromantic love amid their travel and “vagabondage,” and he drills her relentlessly through harsh criticism and late-night rehearsals of Calderón, striving for a standard of perfection beyond what their Lima audience expects.

To counter Camila’s waning interest in theater, Uncle Pio arranges a visit from the poet Vico de Barrera’s granddaughter, for whom Camila performs one of his plays from memory with profound reverence. He also uses talented new actresses to spark Camila’s competitive fire, though her growing technical mastery gradually replaces earlier sincerity.

Viceroy Don Andrés de Ribera—a once-brilliant man now dulled by indulgence and boredom—begins a relationship with Camila. She adores him and learns high-society manners; Uncle Pio accepts this when he sees it refining her performances. The viceroy arranges midnight suppers at which Camila meets the archbishop, a witty, devout man whose philosophical resignation prevents him from addressing Church corruption. Uncle Pio and Captain Alvarado join these gatherings, discussing philosophy and Spain until dawn.

Uncle Pio believes that suffering through love creates essential wisdom and waits for Camila to undergo this transformation. She bears the viceroy three children but does not change as expected. She tires of Don Andrés, returns to casual affairs, and abandons theater to pursue social respectability, inventing aristocratic origins and obtaining fraudulent legitimization for her children. As her status rises, she excludes Uncle Pio from her life. Her son, Don Jaime, is a dignified child who experiences seizures.

Uncle Pio visits her villa, and they meet in the gardens at sunset. Distressed because Jaime has been ill, she insists that he call her Doña Micaela and angrily rejects any theater discussion. When he confesses enduring devotion, she dismisses romantic love as theatrical fantasy but then asks forgiveness, kisses his hand, and leaves.

Camila contracts smallpox, which destroys her beauty. Convinced that all affection toward her was based on her appearance, she becomes a bitter recluse, returns admirers’ gifts, and faces poverty. Uncle Pio gains household access through small kindnesses but is expelled when he accidentally discovers her unveiled, hiding scars with chalk paste.

After some time, Uncle Pio returns before dawn and imitates a weeping girl beneath her window. Calling himself Estrella, he lures Camila outside and begs to take Don Jaime to Lima for a year to educate him. When she refuses, he demands repayment of money owed, exploiting her poverty, though he quickly admits that this was merely tactical. After anguished reflection, Camila agrees, provided the boy wishes to go, giving Jaime a gold coin and a glowing stone for comfort.

Don Jaime meets Uncle Pio at the inn the next day. Uncle Pio carries him on his shoulders because the cart worsens his condition, and they die when the bridge collapses.