The novel alternates between two intertwined timelines set in Colombia. One follows Valentina, a 12-year-old girl living in a decaying Bogotá apartment with her depressed father, Ignacio, whom she calls Papi. The other traces Ignacio's past, from his rural childhood in Ebaguí, a small town in the Tolima region, through his adult double life as a closeted queer man. Binding both timelines is the Magdalena River, Colombia's largest waterway and, in the novel's framing, a repository for centuries of violence and grief. A prologue narrated by Mamadora Eléctrica, a travesti (a Latin American term for a transgender or gender-nonconforming person) and the family's matriarch, establishes the novel's central mythology: Ignacio was chosen by the river to embrace his femininity but refused the calling, unleashing a curse that passes through him to everyone he loves, including Valentina.
In Valentina's present, Papi spends his days in bed watching television and drinking whisky from mugs to disguise the quantity. Valentina's mother, Alma Juan, died years earlier after a blown tire on a rainy night; her body was found in a river, the circumstances never fully explained. The one thing that brings Papi to life is Natalia, a famous Colombian TV host and supermodel who lost a leg in a car accident, whose mother also reportedly drowned in the Magdalena. Valentina sees Natalia's story as a mirror of her own and dreams of becoming a TV anchor, producing a homemade news show with her best friend and neighbor, Jesi. Jesi, a goth-presenting girl, calls Valentina "Río Magdalena" when Valentina spirals emotionally. Their bond is intensely physical; Jesi scratches Valentina's forearms, and Valentina craves the contact.
The only reliable adult in Valentina's life is Tía Mama, Ignacio's travesti mother figure and head of the Eléctrica Family. Tía Mama stocks the fridge, signs school papers, and urges Papi to pull himself together. Meanwhile, threatening letters pile up from Tía Clemencia, Alma's sister, who is pursuing custody of Valentina on the grounds that Papi is unfit. Papi refuses to engage.
Ignacio grows up in Ebaguí in poverty with seven siblings, his grief-stricken mother Encarnación, and his abusive father Clemente, who has an alcohol addiction. At a gathering at Encarnación's shop, a striking neighbor named Lucrecia arrives, and young Ignacio is mesmerized by a yearning he cannot name: He wants to inhabit her elegance, her flowing hair, her manicured fingers. When Ignacio faints during the slaughter of his pet pig, Clemente punishes him by sending him to tend cattle alone on a hill. In solitude, Ignacio begins experimenting: He drapes his soccer jersey over his head like long hair, practices feminine gestures, and performs dramatic scenes for an audience of cows. He catalogs the violence against boys who displayed femininity: neighbors beaten, dragged away, expelled.
Everything shifts when Felipe, Lucrecia's son, appears on the hill: a boy with painted pink nails, tight purple shorts, and unapologetic feminine swagger. After Felipe overpowers him in a fight, they become inseparable. Felipe teaches Ignacio theater and shares stories of boys wearing dresses in Medellín as art. Ignacio brings Felipe to a hidden section of the river with a waterfall, and one day Felipe presents him with his mother's wig. Ignacio puts it on and struts along the rocks, laughing hysterically at his reflection, overwhelmed by joy he cannot sustain. Their physical intimacy deepens gradually, and Felipe declares them bonded for life.
But Ignacio cannot reconcile this private world with the one that claims him. When Felipe takes him to a hidden bathhouse where men engage openly in sex, Ignacio panics, tells Felipe "I'm not like you" (275), and flees. Felipe begins wearing women's clothing in public, and the town reacts with escalating hostility. When Ignacio's older brother Yason, a decorated air force officer, returns and notices Felipe, the consequences are devastating. Yason demands Ignacio prove his manhood, and Ignacio participates in a brutal beating of Felipe, the details never fully revealed but the damage irreversible.
Mamadora Eléctrica's narration picks up years later, after the family has moved to Bogotá. Ignacio reinvents himself as a city boy, but at night he walks the streets, drinking aguardiente, a strong anise liquor, until he finds a community of travestis and eventually Club Aquario, the underground bar Mamadora runs. He transitions from hostile observer to regular. Despite this, Ignacio marries Alma and maintains a double life he calls "La Vuelta" (the return): husband by day, frequenting motels and Aquario at night. He brings infant Valentina to Aquario, where the Eléctrica Family secretly baptizes her in a travesti ceremony. Alma repeatedly leaves for Cartagena when the marriage deteriorates and eventually discovers the deception when a lover carries a too-drunk Ignacio home.
In Valentina's present, the unraveling accelerates. She notices feathers growing from Papi's knuckles, a physical transformation he refuses to discuss. Tía Mama takes her to Arteria Eléctrica, Tía Mama's sister and a legendary travesti seamstress, where Valentina spots a photo of Papi in a white dress and wig. Arteria reveals the past: Alma's visits seeking help, Yason raiding Aquario with armed men, Ignacio being blackmailed, and the murky circumstances of Alma's death. Arteria tells Valentina that Ignacio "couldn't fully be a man for her, who didn't fully know himself" (117).
The Eléctrica Family convenes to strategize against the custody case and decides to hide Valentina and Papi at Tía Mama's finca, a country property in Girardot. On the terrace, Valentina drinks stolen aguardiente with Jesi and confesses her fears. A lip-biting game between them turns intensely charged. Tía Mama slaps Valentina when she sees the blood, warning that they could lose her.
At the finca, Papi's transformation accelerates. Wings replace his arms, claws replace his legs, a beak hardens. He stops speaking. Valentina sleeps curled next to his bird body, checking her own skin for signs of change, furious that Papi gets to escape while she remains the same. During the days that follow, she retreats to a pond on the property whose underground currents connect to the Magdalena. In anguished rage, she yanks feathers from his chest, drawing blood, trying to climb inside his body and refuse to let him leave.
When Tía Mama and Jesi arrive with news that Clemencia has hired private security to find them, Jesi reveals she has been seeing another girl. Devastated, Valentina runs through the jungle and collapses in the town plaza. In a church, she meets Magdalena, a runaway girl from Barranquilla living with a Santería practitioner and travesti godmother named La Divi. Valentina tells her story, and they kiss. La Divi tells Valentina she carries "the curse of the river" (316) and gives her herb-infused river water for prayer.
Valentina returns to find that dogs have attacked the black dove Papi has become. He lies on the blanket, one wing torn, one leg missing, eyes still open. Valentina wraps Papi in the blanket and carries him to the pond. She spits La Divi's water onto the earth, praying through song. The water fractures the soil, and the pond merges with the underground currents of the Magdalena. On a raft of the blanket, Papi breathes his last breath as Valentina surrenders to the river.
The final chapter returns to an afternoon at the river with Felipe before everything was destroyed. Felipe's head rests on Ignacio's chest. For one suspended moment, Ignacio imagines the river carrying them both away. The novel ends on this image of two boys held together briefly by impossible love.