Estrella is a young girl on the verge of womanhood. Her family includes her mother Petra, four younger siblings, and an older man, Perfecto. The family are migrants, living wherever they find work picking crops. As the story begins, the family are driving through an orchard to a run-down bungalow, where they will stay during the coming weeks. Petra, who is devout, sets up an altar in the house, where she can pray before statues of Jesus, Mary, and Joseph. She worries about keeping her family safe. She always makes sure there is a circle drawn in the dirt around the house at night, to keep away scorpions. Not far from the house stands an old, decaying barn. It fascinates the children, especially Estrella. 

Estrella’s father left the family some years ago. When Perfecto became Petra’s companion, Estrella resented him. However, they get along better now. He taught her how to use the tools in his toolbox, and sometimes they work on small jobs together, like patching a hole in a wall. Privately, however, Perfecto is unhappy and anxious. He was once married, but the children from that marriage are grown, and his wife died of cancer. Now Petra is pregnant, and the burden of being a family man at his age increasingly seems too much to bear. He is thinking of leaving. When he is hired to dismantle the barn, he sees it as an opportunity to earn enough money to go back to Mexico by himself. He tries to persuade Estrella to help him with the job.

Alejo and Gumecindo are cousins. Like Estrella’s family, they work in the fields. They also earn a little extra money on the side, by stealing peaches from the orchard to sell on weekends. Alejo and Estrella meet and are attracted to one another. Petra is unhappy about this development, but she knows there isn’t much she can do. One day, while Alejo is up in a tree picking peaches, a crop-dusting plane flies overhead and drenches him with pesticide. Alejo feels sick, but at first he is able to keep working. He and Estrella spend more time together and grow closer. Soon, however, Alejo becomes too sick to work. He is also too sick to travel. Gumecindo wants to look after his cousin but also needs to return home for school. Petra solves Gumecindo’s dilemma by agreeing to take Alejo in and care for him. Perfecto objects, but Petra sees Alejo’s situation as a test of her willingness to care for others in need. 

Unfortunately, it eventually becomes clear that Alejo needs professional treatment. The family takes him to a clinic, where a nurse charges the family ten dollars to tell them that Alejo needs to go to a hospital. The family needs that money for gas, but Perfecto pays the nurse, not knowing what else do to. Estrella, out of patience, bashes the nurse’s desk with a crowbar and makes her give back the money Perfecto just paid. The family takes Alejo to the hospital and leaves him there. Alejo begs Estrella to stay by his side, but she cannot. 

Back at the house, Perfecto realizes that the police are probably searching for the family. The best time to leave is now. Petra, sensing what is on Perfecto’s mind, goes inside and prays at the altar. When the statue of Jesus falls and breaks, Petra thinks to herself that Perfecto is the one to repair it. During the commotion, Estrella steps outside. Ignoring Petra’s warnings, she makes her way to the mysterious barn and climbs up onto the roof. As the story ends, Estrella sits beneath the starry sky and feels the power of her own heart.