Rome, June 1800
The church of Sant’Andrea della Valle. Noon.
Angelotti, an escaped political prisoner, takes refuge inside the church of Sant’Andrea della Valle. As he finds a place to hide, a Sacristan appears followed by the painter, Mario Cavaradossi. Cavaradossi is working on a picture of Mary Magdalene, inspired by Angelotti’s sister, Marchesa Attavanti.
When the Sacristan leaves, Angelotti emerges from his hiding place. Cavaradossi, recognises hims and promises to help, but tells him to hide when his lover, the opera singer Floria Tosca, arrives. She is furious that Cavaradossi’s painting of the Madonna is a portrait of another woman. Once Tosca has gone, Angelotti reappears. A cannon shot is heard, signalling that the police have discovered Angelotti’s escape, and he and Cavaradossi flee to the painter’s house.
The Sacristan returns, followed by clerics and choirboys, celebrating rumours of Napoleon’s defeat at the Battle of Marengo. The general excitement is cut short by the entrance of Scarpia, Chief of Police, on the trail of Angelotti. When Tosca arrives looking for Cavardossi, Scarpia plays upon her distrust of the Marchesa Attavanti in the hopes of discovering Anglelotti’s hiding place. With her jealousy enflamed, Tosca leaves in a rage and Scarpia orders his men to follow her, hoping she will lead him to the fugitive. A Te Deum of thanksgiving begins and Scarpia declares that he will bend Tosca to his will.
Scarpia’s apartment in the Palazzo Farnese. Evening.
In his apartment above the Farnese Palace, Scarpia anticipates the pleasure of having Tosca in his power. Having not been able to find Angelotti, Scarpia’s henchman Spoletta arrives at the apartment with news that they have instead brought Cavardossi in for questioning.
Interrogated by Scarpia, Cavaradossi denies any knowledge of Angelotti and is taken away to be tortured. When Tosca arrives, Scarpia begins interrogating her, using Cavaradossi’s screams to torment her; under this duress, Tosca finally reveals the hiding place.
Cavaradossi is brought back in, badly hurt and hardly conscious. He’s furious to find that Tosca had given Scarpia Angelotti’s location, but at that moment news arrives that the report of a royal victory at Marengo was incorrect and that Napoleon has in fact won. When he shouts in defiance to the news, Scarpia orders Cavaradossi’s execution.
Alone with Scarpia, Tosca begs for her lover’s life and Scarpia names his price: she must give herself to him. Seeing no alternative, she agrees, and Scarpia appears to order Spoletta to perform merely a sham execution. Once Scarpia has granted safe‑conduct for Tosca and Cavaradossi to escape from Rome, Tosca stabs him to death, just as he demands ‘payment’ from her.
The battlements of the Castel Sant’Angelo. The hour before dawn.
A shepherd boy is heard singing in the distance. Cavaradossi enters to await his execution. He tries to write a letter of farewell to Tosca and reflects on the joy she has brought him. Tosca arrives and discloses her plan for their escape. The firing squad duly performs what Tosca believes to be a mock execution. She realises too late that Scarpia has deceived her: the execution was real and Cavaradossi is dead. News of Scarpia’s murder has broken. As Spoletta and his men rush in to arrest Tosca, she leaps over the parapet to her death.