Eleven-year-old Maya plays with plastic toy horses in her bedroom, imagining ghost horses flying through the sky. The faded toys once belonged to her mother, who died six years ago in an accident. Maya has lived with her paternal grandmother, Agnes Menetti, ever since, enduring at least 18 different housekeepers.

Maya retrieves a photo showing her mother laughing and riding on a brown-and-white horse. She notes her resemblance to her mother; Maya has the same delicate frame, russet-red hair, and violet eyes, although her skin is darker. She places the photo and corresponding toy horse on her windowsill, looking out past the manicured Pasadena neighborhood and imagining her mother’s joyful life with horses—a life Maya knows nothing about. She realizes that she cannot remember her mother’s laughter or her own.

The new housekeeper, Morgana, enters and reminds Maya that she should be doing homework, not playing. Maya lies, claiming that she finished her work and that previous housekeepers left her alone. Morgana, who is well-paid and determined to please Grandmother, asserts that she will be different. When Morgana asks about the horses, Maya spins an elaborate lie, claiming that her parents died in a snorkeling accident in Costa Rica when a motorboat struck them. She also claims that her father saved her by tossing her clear, then asserts that she keeps the toy horses hidden because Grandmother has an intense fear of them, due to a riding accident.

After Morgana leaves, Maya scolds herself for taking the risk of exposing the toy horses and hides the shoebox in her closet. She meticulously checks that everything in the room meets Grandmother’s exacting standards before heading downstairs at six o’clock. She passes a wall of framed photos showing only her grandmother and her grandmother’s son, Maya’s father; Maya’s mother is cut out from all pictures, save the young girl’s hidden snapshot.

Artemisia gives a final push, and the foal slides completely into the world. When she stands, the umbilical cord breaks. She licks the damp, motionless baby until he finally twitches, stirs, and begins to breathe. The foal, later named Klee, wobbles to his feet, collapses, then rises again. After several awkward attempts, he finds a teat and nurses for the first time.

Artemisia feels content and in no hurry to rejoin Sargent’s band, just as she stayed away for a week after Mary’s birth. As Klee’s coat dries, his brown-and-white tobiano markings emerge, mirroring Artemisia’s own pattern. Against the approaching dawn, the light sections of their coats glow while the dark portions vanish into the night, making them look like two broken spirits floating in the twilight.

Agnes Menetti, Maya’s 88-year-old grandmother, enters the dining room. Maya reflects that Grandmother used to be active but has not left the property in six years. Grandmother inspects the table, then orders Morgana to remove fallen leaves and call in some painters to restore the scratched patio furniture. Maya notes that everything on the property is obsessively repainted eggshell white.

When Grandmother asks about school, Maya begins sharing a pleasant memory of her teacher, Mrs. Webster, but Grandmother interrupts, worried that the school might have a frivolous curriculum. To protect her school, Maya lies and claims that the activity was an important educational technique. Grandmother expresses her expectation that Maya will be an excellent student like her son, Gregory. During the silent dinner, sounds of children playing outside filter through the window.

Morgana returns carrying the shoebox of horses, revealing that she found Maya playing with them. Grandmother examines the photo of Maya’s mother on top. Unable to fabricate a lie quickly enough, Maya admits that her mother gave them to her. Grandmother blames Maya’s mother’s obsession with horses for Gregory’s death, explaining that he met her on a painting trip in Wyoming and brought her to civilization, but she would not give up riding. The accident that killed them both occurred while they were traveling to a riding excursion. Morgana exposes Maya’s lie about a boat accident, but Grandmother dismisses it as childish imagination. She orders Morgana to throw the box in the alley trash, then revokes Maya’s Saturday library privileges.

Upstairs, Maya realizes that the trash was collected only yesterday, leaving her one week to retrieve her horses. She comforts herself by recalling the housekeepers that she has successfully sabotaged in less time.

Artemisia senses it is time to return to the band with Klee. She leads him over a hill and neighs an announcement; the other horses turn to greet them. Sargent nickers a welcome but remains on guard. Georgia approaches to sniff the new foal, and when Wyeth becomes too bold, Mary intervenes protectively before nuzzling her new brother.

After Artemisia urinates, Sargent covers her scent with his own to mark his territory. He then approaches to meet his son. Klee instinctively shows submission by pulling back his lips and clapping his teeth together. Satisfied, Sargent sniffs the foal and grooms Artemisia, who returns the gesture. Throughout the night, Klee nurses frequently while Artemisia watches over him.

Maya stands on her balcony, worried that someone might take her horses from the trash before she can retrieve them. To sabotage Morgana, she dirties the woman’s clean school blouse by mopping the deck with it. Through the neighbor’s window, she watches a mother tenderly combing her daughter’s hair and feels a sharp longing.

During Grandmother’s nightly inspection, the dirty blouse is discovered. Grandmother scolds Morgana, who remains unflustered, disappointing Maya. On Sunday, Maya and Grandmother review photo albums of her father. When Maya comes across a photo where her mother’s image has been cut out, leaving only a hand and wisp of hair, her anger swells. Her anger intensifies the next day when Grandmother forbids Maya from attending school, claiming that she looks flushed.

After Grandmother leaves a painter’s estimate and pen on the coffee table, Maya seizes her opportunity for more sabotage. She changes the paint color number on the order form from eggshell white to a vivid pink, then deliberately scuffs the white floor. On Tuesday, Grandmother discovers that the patio furniture has been painted the wrong color. Within the hour, Morgana is fired. While Grandmother recuperates, Maya retrieves the shoebox from the alley trash and vows to keep it safe.

A few days later, the new housekeeper, Valentina, wakes Maya in distress. Grandmother is confused, calling Valentina by another name and requesting a recipe from two years ago. Maya helps locate the instructions. At breakfast, Grandmother seems unsteady. She tastes the eggs, declares that they contain pepper when they do not, and accuses Valentina of lying. When Maya defends Valentina, Grandmother suddenly hurls her plate against the wall. Her head falls forward and strikes the table with a thump. As Valentina calls for help, Maya realizes that Grandmother might not wake. She runs to her, calling her name, but Grandmother’s body is limp. An ambulance siren approaches.

As lead mare, Artemisia guides her band away from a gully containing a horse skeleton. She leads them toward a watering hole but pauses when she sees an aggressive rival stallion’s band drinking there. After they leave, she takes her group forward. Georgia nudges Klee to keep him from straying. Sargent patrols from behind, taking attendance before drinking and inspecting the area for danger.

Klee plays energetically, pestering Mary, Wyeth, and then his father. When the playful colt bothers Sargent, who is standing guard, Artemisia intervenes. She repeatedly blocks Klee’s attempts to rejoin the others until he becomes anxious and approaches her penitently. Artemisia relents and allows him back into the group.

As Maya sits on an airplane flying over Nevada and Utah, she reflects that the last 24 hours have felt like months. She recalls Grandmother being taken away in an ambulance and a doctor delivering dire news. Grandmother’s lawyer, Mr. Benedetto, arrived at the hospital and later explained that Grandmother had died from a massive stroke. The house would go to a heritage league, personal items would be stored, and a trust had already been set up for Maya’s college education.

When Mr. Benedetto told Maya that she would go to the Limners in Wyoming, the young girl was initially confused, having never heard of them. Mr. Benedetto discovered from Grandmother’s will that custody was meant to be split between Grandmother during the school year and Maya’s maternal family, the Limners (her grandfather Walter, his brother Frederick, and his sister Violet). Grandmother had violated this arrangement for six years. Maya repeated what Grandmother had told her: that they were uneducated, crass “hillbillies.”

Alone, Maya worried about why her mother’s family never contacted her, not knowing that Grandmother had prevented it. Valentina helped her pack her single suitcase. Maya wandered through the silent, plastic-covered house, touching her father’s photos and the milk-glass vases for the first time.

The narrative returns to the present. As the airplane lands, Maya clutches her box of horses, and a flight attendant asks if she is visiting or going home. The young girl replies that she does not know.