Usandizaga's score certainly avails itself of verismo manners, specifically through some sophisticated post-Tristan harmonic twists, and his melodic inspiration is uneven. Still, there is a single-mindedness about this music, a focus of energy which makes it not quite like anything else in the repertoire. The great majority of zarzuelas - including some of the finest - sound at least twenty or so years behind the musical fashion of their time, but that cannot be said of Los golondrinas. There is a modernity about it which hasn't quite faded, and the best of Usandizaga's music remains haunting and tender to a special degree.
Act 1 - A dressing cabin in the square of a small town in Castile. After the stirring Preludio, we meet the touring theatre troupe come to provide a show for the local fiesta. The leader of the company, Roberto, is a hardened drinker who has known better days. With him are his young daughter Lina, a promising singer-dancer; two bright hopefuls, Juanito and Boby; the beautiful leading lady Cecilia; and Puck, talented mainspring of the operation (Escena: "Aqui tiene usted la peluca".) Puck is involved with Cecilia, but she is ambitious, sickened by the continual wandering from town to town, and yearns for the wealth and fame her beauty deserves. Lina, who is herself hopelessly in love with the handsome Puck, sees which way the wind is blowing, and Cecilia tells her a little of her unhappiness (Dúo: "Camino sempre...") Puck's love is no compensation for this living from hand to mouth. Not for her the noble life of the road of which Puck sings so passionately (Romanza: "Caminar, caminar".) His passion merely irritates Cecilia (Dúo: "Fuego de paja en el viento",) her frustration boils over into withering scorn, and Puck - goaded past breaking point - hits her and rushes away in self-disgust. Young Lina meanwhile sings sadly of her own unrequited passion, hoping that things will turn out for the best (Romanza: "Me diches che ya no mi quieres".)
The crowd enters, ready to enjoy themselves at the show (Coro: "Noche clara de San Juan".) Lina, seeing Cecilia heading off with her suitcase, tries in vain to stop her from leaving them in the lurch. She tells Lina that she must have the money, fame and comforts which are now denied her, and Lina's plea that she is breaking Puck's heart falls on deaf ears (Escena: "No lo sé, voy un busca de algo".) Cecilia leaves. Lina, blaming herself and knowing she will have to break the news to Puck - who is out front starting his pitch for the show - consoles herself with the thought that perhaps, after all, things will fall out for the best.
Act 2 - A theatre in a large city. The combined talents of Puck, Lina and the two young comedians has attracted the interests of a powerful impresario, and now they are to make their debut at his theatre in the capital as the "Family Sanders" with a new dance-piece or pantomima put together by Boby and based on the well-known characters and story of the Italian commedia del'arte, Columbina-Lina, Harlequin-Puck, and Pulchinello. It is spring, and Lina hopes that she and Puck can put old memories behind them (Romanza: "En viejas memorias".)
Meanwhile Juanito, who is to play Pulchinello, has his own problems, being pestered beyond endurance by Puck's dresser Leonor and the whole of the admiring female chorus (Canción y Coro: "Juanito, Juanito, Juanito".) Lina confesses to Leonor that she loves Puck; but when the kindly dresser tells her that she is sure the feeling is reciprocated, Lina admits that deep down she knows he can feel no more than a brotherly love for her. Puck comes in with Juanito: all is ready for the stage show.
Their Pantomima, a substantial orchestral number incorporating mime action and a Serenata for Harlequin ("Columbina, Columbina bella") is a huge success. Another artist had been watching their triumphant performance: Cecilia, now herself wildly successful as "La Bella Nelly". With her powerful protector Count Stein in tow, she tells the impresario she wishes to join his company, an offer he cannot refuse. Puck and especially Lina are rapturously applauded, and things are looking up even for Roberto, who is regaining some of his old self-respect as nominal leader of the troupe (Coro y escena final: "¡Que Linda es Columbina!".) When he discovers Cecilia in the crowd, Puck moves towards her. The Count sweeps her away, and Lina tries to stop Puck from following, but he shakes her off violently and leaves.
Act 3 Scene 1 - Lina's dressing room. In spite of their triumph and his growing affection for the faithful and increasingly famous Lina, Puck is remote and distant from her (Dúo: "¡Oh, Puck!, Por tí mi corazón".) Suddenly, he hears a familiar laugh from the dressing room. His instant distraction at the sound of his old love fills Lina with terrible foreboding. The unexpected return of Cecilia has divided the "Family Sanders." Although Roberto is all for it, Lina is adamant "La Bella Nelly" must not join the company, especially when Cecilia insolently tells her she will reclaim Puck whenever she wants. Then Puck reappears and Lina, seeing that her situation is hopeless, leaves him alone with her rival. Cecilia spitefully goes along with his passionate avowals, pretending to feelings she does not have. They slip away together (Dúo:"Cecilia... ¡Habla!",) after which a vibrant Intermedio recaps many of the work's major melodies.
Scene 2 - The same. Lina returns to her dressing room, and when a clearly distraught Puck materialises and stammers out a final farewell, she demands to know what has happened. Puck decides to speak out (Dúo: "¡Adios!... Me fui con ella".) He tells her that when he took Cecilia into the wings and tried to kiss her, she laughed in his face (Solo: "¡Se reía!") and told him she loved another. Mad with jealous rage, Puck has strangled her. Lina is horrified, but still clings to her beloved when the police rush in with the full company to arrest him. Boby accuses Puck of Cecilia's murder, and he confesses. Before they are finally torn apart, Puck asks for and receives Lina's forgiveness (Final: "¡Estrella de min camino".) Heartbroken, she collapses into her father's arms as the curtain falls.