Prologue
The velvet curtain rises. Tonio appears among vacant theatre chairs. He addresses the audience. He reminds the audience that actors have feelings too, and that the show is about real people.
Act 1
Theatre-goers meet their favourite commedia troupe, famous artists: Canio, his wife Nedda, Tonio and Beppe. Canio describes the night's performance: the troubles of Pagliaccio.The crowd is excited about the upcoming entertainment. The men suggest drinking at the tavern. Canio and Beppe accept, but Tonio stays behind. Someone teases Canio that Tonio is planning an affair with Nedda. Canio warns everyone that while he may act the foolish husband in the play, in real life he will not tolerate other men making advances to Nedda.
Canio removes the resulting tension with public recognition of love for his wife - Nedda. Saying goodbye to the artists until the evening, the fans arrange a game with running beams of searchlights. Left alone, Nedda tries to understand her own desires.
She reminds the birdsong her mother has sung in her childhood. It comforts her. Tonio watches her and wants to confess his love for her, but she laughs. Enraged, Tonio grabs Nedda, but she takes a whip, strikes him and drives him off. Tonio vows to avenge the insult. Silvio, who is Nedda's lover, comes from the tavern, where he has left Canio and Beppe drinking. He asks Nedda to elope with him after the performance and, though she is afraid, she agrees. Tonio, who has been eavesdropping, leaves to inform Canio so that he might catch Silvio and Nedda together. Canio and Tonio return and, as Silvio escapes, Nedda calls after him, "I will always be yours!”
Canio chases Silvio, but does not catch him and does not see his face. He demands that Nedda tell him the name of her lover, but she refuses. He threatens her with a knife, but Beppe disarms him. Beppe insists that they prepare for the performance. Tonio tells Canio that her lover will give himself away at the play. Canio is left alone to put on his costume and prepares to laugh. But his heart is broken.
An interval.
Act 2
As the crowd arrives, Nedda whispers a warning to Silvio, and the crowd cheers as the play begins. Nedda plays Colombina, Beppe - Arlecchino, Tonio - Taddeo, Canio - Pagliaccio in the performance.
Colombina's husband Pagliaccio has gone away until morning. She anxiously awaits her lover Arlecchino, who comes to serenade her from beneath her window. Taddeo returns and confesses his love, but she mocks him. She lets Arlecchino in through the window. He boxes Taddeo's ears and kicks him out of the room, and the audience laughs.
Arlecchino and Colombina dine, and he gives her a sleeping drug to use later. When Pagliaccio returns, Colombina will drug him and elope with Arlecchino. Taddeo bursts in, warning that Pagliaccio is suspicious of his wife and is about to return. As Arlecchino escapes through the window, Colombina tells him, "I will always be yours!"
As Canio enters, he hears Nedda saying those same words! He tries to continue the play, but loses control and demands to know her lover's name. Nedda, hoping to keep to the performance, calls Canio by his stage name "Pagliaccio," to remind him of the audience's presence. He sings that if his face is pale, it is not from the stage makeup but from the shame she has brought him. The crowd, impressed by his emotional performance, which they do not realize is real, cheers him.
Nedda, trying to continue the play, admits that she has been visited by the innocent Arlecchino. Canio, furious and forgetting the play, demands the name of her lover. Nedda swears she will never tell him, and it becomes apparent that they are not acting. Silvio begins to fight his way toward the stage. Canio, grabbing a knife from the table, stabs Nedda. As she dies, she calls: "Help! Silvio!". Silvio attacks Canio, but Canio kills Silvio. The horrified audience then hears the celebrated final line:
"The comedy is finished!"
