The play opens in 1476 in Spain, at a meeting between the 17-year-old Master of the Order of Calatrava, Rodrigo Téllez Girón, and his Commander, Fernán Gómez de Guzmán. After the recent death of King Henry IV of Castile, there is a dispute over who should rule the kingdom of Castile. Some are loyal to Henry’s daughter Juana and her husband, King Alonso of Portugal, while others are loyal to Henry’s sister Queen Isabel of Castile and her husband, King Fernando of Aragon. The Commander reminds the Master of his family’s loyalty to Alonso, and he convinces the Master to take an army to capture the key stronghold of Ciudad Real from Isabel and Fernando, claiming that this will allow the young Master to prove his worth in battle.
The play picks up some days later, in the small town of Fuente Ovejuna, where the Commander lives. The young peasant Laurencia is telling her friend Pascuala how much she hates the Commander. The Commander pursues her relentlessly, but he has had sex with many of the women in town and quickly discards them afterward, and she doesn’t want this to happen to her. She notes that she hates men generally, because they all lie to women to get them into bed and then abandon them in the morning.
Soon after this discussion, the Commander returns from his campaign against Ciudad Real—it was a bloody fight, but the Master and Commander prevailed. The townspeople welcome the Commander home and give him lavish gifts for his success, and he thanks them for their love. As the crowd disperses, he instructs his servants, Flores and Ortuño, to grab Laurencia and Pascuala and lock them in a nearby stable so that they can be part of his spoils of war, but Laurencia and Pascuala fight the men off and run away.
At Queen Isabel and King Fernando’s court, two aldermen from Ciudad Real arrive. They explain that the Ciudad Real’s citizens are loyal to “the Catholic Kings” (meaning Isabel and Fernando), and though they tried to fight off the Master’s army, they were unsuccessful. They ask for help in regaining control over their town, and the King sends two armies to recapture the city.
Back in Fuente Ovejuna, Laurencia and Frondoso, a young villager, are talking in the woods. Frondoso is madly in love with Laurencia, but she hasn’t really thought about marriage and is annoyed that the whole town gossips about them. Just then, the Commander comes down the path while hunting, and Frondoso hides in the trees. Seeing Laurencia, the Commander drops his bow and arrow and starts to force himself on her, but Frondoso emerges from his hiding place, picks up the bow, and points it at the Commander. Laurencia is able to escape, and Frondoso walks away—but still clutching the bow so that the Commander can’t kill him with it. After Frondoso departs, the Commander vows to get revenge on him.
Soon after, at a town council meeting, the Commander tells Esteban (one of the town magistrates and Laurencia’s father) that his daughter needs a talking to—she refuses to submit to his desire in the way that many other women in the town have. Esteban and the other council members point out that the Commander has been dishonoring the women of the town, as well as many of the men by sleeping with their wives. The Commander scoffs, saying that the peasants don’t have honor to begin with. He disbands the meeting, angry and insulted. After the other men leave, a soldier reports to the Commander that Isabel and Fernando have sent an army to Ciudad Real, and the Master is asking for his help in maintaining a hold on the city. The Commander agrees to go.
As the Commander rides out, Flores and Ortuño try to abduct a woman named Jacinta to bring with them to Ciudad Real for the Commander’s pleasure. When another villager, Mengo, defends her, the Commander orders his henchmen to flog Mengo severely. When the Commander arrives at Ciudad Real, he and the Master are quickly defeated by Fernando and Isabel’s forces.
Later, Laurencia and Frondoso meet up once more. Moved by his bravery in the woods, Laurencia agrees to marry Frondoso. They ask her father, Esteban, for permission, who agrees to the match, and Frondoso is overjoyed. They wed soon after, but the Commander, returning from his defeat at Ciudad Real, interrupts the festivities. He arrests Frondoso and abducts Laurencia; when Esteban tries to protest, the Commander has Esteban beaten.
That night, the councilmen meet in secret, wondering what they can do to save Laurencia and Frondoso. Esteban points out that the Commander has dishonored all of them, and they should band together. Just then, Laurencia arrives at the meeting, completely disheveled with cuts and bruises all over her body—she had to fight off the Commander’s servants to prevent them from raping her. She calls on the men to act and defend the women’s honor and their own. The men agree to take up her cause and make the Commander pay for what he’s done.
After the men leave to storm the Commander’s house, Laurencia gathers the women, imploring them to take up arms and defend their honor as well. At the Commander’s home, he is about to hang Frondoso when the villagers burst through the doors, shouting, “Fuente Ovejuna!” and calling for death to tyrants. The men go after the Commander, while the women attack Flores and Ortuño.
The next day, Flores arrives at Isabel and Fernando’s court, having escaped the women’s wrath. He explains that the faithless villagers in Fuente Ovejuna unjustly rose up against the Commander, throwing him from a window and dismembering him. The King agrees to launch an investigation into what happened and punish those responsible.
Back in Fuente Ovejuna, the villagers rejoice at having killed the Commander. But when the King’s judge arrives to investigate the murder, Esteban tells all of the townspeople to say that “Fuente Ovejuna did it.” Although many villagers are tortured in the judge’s attempt to glean information from them, they all stick to the story. Then Isabel and Fernando pay a visit to Fuente Ovejuna, where the Master humbly asks for their forgiveness for his treachery, and they welcome him in their court. The judge then summarizes his investigation, and Esteban, Frondoso, and Laurencia plead their case to Isabel and Fernando. They explain that they were rebelling against the Commander’s brutal tyranny. Hearing the villagers’ case, the King says that the crime was serious, but because there is no evidence, all of the townspeople must be pardoned. Frondoso thanks the King for being a wise and just ruler.
