Act 1. Madrid, San Javier Square, outside an inn. It is 1868, and the regime of Queen Isabel II is under threat from the revolutionary republican movement. After the orchestral Introducción we meet the innkeeper, Mariana, chatting in the sun with her lodgers (Escena: "Mi madre me criaba".) These include a seamstress, Rosita, the republican Don Luís Nogales and his enthusiastic young supporter Aníbal. A Savoyard accompanying himself on a barrel organ sings a sad story about a girl and an unfaithful soldier (Canción: "Marchaba a ser soldado".) The elderly former palace clerk, Don Florito Fernandez and his daughter Luisa join Mariana. Luisa's fiancé Javier has recently been made a Colonel, and he is not paying Luisa his accustomed attentions. Jeromo, a servant of the monarchist Duchess Carolina whose house is just across the square, warns Mariana about Nogales' dangerous activities. Luisa leaves for Mass. Javier just misses her, and is thoroughly scolded by Mariana for his nonchalent attitude. He sings of his ambition and impatience with the quiet life of Madrid (Romanza: "De este apacible rincón de Madrid".) Overseen by the Duchess from her balcony, Aníbal tries to talk Javier into joining the revolutionary movement and introduces him to Nogales.
The men leave, and Luisa returns. Mariana strongly advises her to forget Javier and think about marrying a rich landowner, Vidal Hernando, who has come to Madrid to look for a wife and is on his way to the inn. Mariana introduces him to Luisa. She indulges herself in some mild flirtation, but warns Vidal that she is deeply in love with another man and leaves (Dúo: "En mi tierra extremeña".) When Aníbal tells him that Javier is joining the revolutionaries, Vidal has no hesitation in declaring himself a staunch monarchist - the landowner will fight to win Luisa from the soldier. Javier returns, looking for Luisa. The Duchess Carolina takes the opportunity to further her acquaintance with the handsome young Colonel (Dúo: "Caballero del alto plumero".) Under her seductive influence - and much to the astonishment of Aníbal, Nogales and Vidal - Javier's political allegiance takes another about turn. As Luisa Fernanda returns, just in time to see Javier sauntering away with the Duchess Carolina on his arm, Vidal promptly declares himself a revolutionary and proposes to her. Hurt and confused, Luisa faints into his arms as the act ends.
Act 2 Scene 1. The Paseo de la Florida. Mariana and Rosita have been persuaded by Carolina to organise a charity collection outside the Oratory of San Antonio, next to a drinks stall run by the taverner Bizco Porras. Street vendors and musicians mingle with the crowd; and young men chat with a group of ladies carrying parasols. These 'sombrilleros' are visiting the Oratory to ask St. Anthony to send them lovers, and Javier and Carolina join them in the famous Parasol Mazurka (Mazurca de las sombrillas: "A San Antonio".) Their flirtatious duetting is watched by Mariana; and when Luisa and her tired father arrive, the innkeeper swiftly puts them in the picture. Luisa unconcernedly explains that she has come here to meet Vidal, and taking Mariana off for a stroll leaves Don Florito in charge of the collection table with Rosita. Aníbal shares bad news with Bizco and Nogales about a bungled republican attack, but Bizco is more concerned at the lad's failure to deliver some lemons promised for the stall.
Carolina takes over at the table, soon to be joined by Vidal. She offers him a substantial sum to join the monarchist movement, but he refuses, quoting the fable of the village idiot who believed be was a swallow - Vidal at least has no intention of flying above his station (Dúo: "Para comprar a un hombre".) Luisa returns, apologising to Vidal for being late, and when Vidal assures her that he will remain a republican for her sake Luisa, irritated by Javier's arrogant possessiveness, tells the soldier that she prefers the landowner after all (Terceto: "¡Cuanto tiempo sin verte, Luisa Fernanda!".) Carolina, finding the charity table hasn't had much luck, proposes to add to the proceeds by auctioning herself off as a dance partner (Escena: "Señoras y caballeros".) Vidal easily outbids the jealous Javier; but insultingly passes on his prize dance to the soldier, who quietly confirms his determination to fight his rich rival.
Scene 2. The Calle de Toledo at dawn. The rebels are gathering. Bizco and a churros-seller discuss the troubled situation. Nogales makes an impassioned speech to his rag-bag of an army, which goes off in good heart to fight and die in the name of liberty.
Scene 3. The Courtyard of Bizco's Tavern. Waiting anxiously for news of the fighting, Mariana tells the rosary with Luisa and some neighbours. The wounded Aníbal staggers in and reports how bravely Vidal has fought, before being carried forcibly off to bed. Vidal disclaims heroic status: he merely fought for love of Luisa (Romanza: "Luche la fe por el triunfo".) When Don Florito tells them that Javier is leading a counter-attack for the monarchists, Luisa herself defies Carolina with surprising revolutionary fervour. The attack fails, and Javier is led in a prisoner by Nogales. The crowd bays for his death as the Final: "¡Muera el prisionero!" begins. Luisa steps in and bravely defends him, just before the courtyard is invaded by Vidal and the republicans in flight from a fresh troop of hussars. The soldiers free Javier and announce the defeat of the insurgents. Vidal, admitting defeat on all fronts, is content to be arrested as chief rabble-rouser by Javier, but Nogales steps in and claims that honour for himself. The troops take Nogales away, Javier and Carolina embrace and leave together, and Luisa promises to marry the wounded but ecstatic Vidal.
Act 3. Vidal's country estate 'La Frondosa', at Piedras Albas in Extramadura. The revolution has finally succeeded. Carolina has been exiled to Portugal, whilst Javier has disappeared, reported missing after the battle of Alcolea in which Queen Isabel II lost her throne. Mariana, Luisa and her father have joined Vidal to prepare for the wedding. He leads a chorus of vareadores (harvesters) in a celebrated song, in praise of his lovely sweetheart (Coro y Romanza: "¡Ay mi morena, morena clara!".) Aníbal rushes in, announcing that he has found Javier in Portugal and has brought him back - Vidal had sent the boy there to fetch a wedding dress for Luisa, but in his excitement Aníbal has foolishly forgotten to bring it back.
Javier, wounded and broken, has asked Aníbal to persuade Luisa Fernanda to meet him once more before the marriage. Luisa agrees, and in a moving duet she admits to Javier that she still loves him, but tells him that she must stand firm to her promise to Vidal. (Dúo: "¡Cállate, corazón!".) Javier wanders away, as Luisa insists to Vidal that she will go through with the wedding. The guests, led by Aníbal, gather to dance and enjoy themselves (Final: "El Cerandero se ha muerto";) but when Javier returns in despair to plead with Luisa once more, Vidal realises that Luisa will never love him. Despite her guilty objections, he releases her from her promise and generously encourages her to leave with Javier. Telling the harvesters to get on with their work, Vidal is left alone to grieve, with only the memory of his lost 'morena' - dark beauty - to comfort him.