ACT I
Cesare Angelotti, an escaped political prisoner, enters the church of Sant’Andrea della Valle and hides within a chapel. An artist and revolutionary, Mario Cavaradossi, comes in to work on his portrait of the Madonna, inspired by the Marchesa Attavanti. While an old Sacristan performs his morning duties, Cavaradossi compares the blonde Madonna he is painting to the raven beauty of his lover, the singer Floria Tosca. When the Sacristan leaves, Angelotti emerges from hiding and asks for Cavaradossi’s help. They are interrupted by the entrance of Tosca, who has come to see her lover. Cavaradossi, who keeps Tosca from seeing Angelotti, has to quiet her jealous fears about the woman in his portrait of the Madonna before she will leave. The two men hear a cannon shot—a signal that Angelotti’s escape has been discovered. They flee to hide Angelotti at Cavaradossi’s villa.
The Sacristan and the acolytes enter, excited about the army’s supposed victory over Napoleon. Scarpia, chief of police, enters, having tracked Angelotti to the church. Tosca returns to find her lover gone. Scarpia sows seeds of jealousy in Tosca, suggesting that her lover is having an affair with the Marchesa. Tosca, crazed with jealousy, rushes out to find the painter. Scarpia sends his minions to follow her, hoping that Tosca will lead them to Cavaradossi and Angelotti. As a joyful crowd fills the church to celebrate Napoleon’s supposed defeat, Scarpia, ignoring the celebration, dwells on his lust for Tosca.
ACT II
Scarpia, in his headquarters in the Farnese Palace, sends for Tosca. Spoletta arrives with Cavaradossi, and Scarpia interrogates the painter about Angelotti’s whereabouts. He gets nowhere, and sends him off to the torture chamber adjacent to his office. Tosca appears, and her actions reveal to Scarpia that she knows something about Angelotti. He makes her listen to Cavaradossi’s torture. She can’t bear it, and tells Scarpia where Angelotti is hiding. Scarpia cruelly lets Cavaradossi know that Tosca has talked. A message comes that Napoleon has won, and Cavaradossi indulges in a cry of victory and defiance. Cavaradossi is dragged to prison, and Tosca is left to bargain with Scarpia for her lover’s life. Scarpia suggests that Tosca yield herself to him in exchange for the painter’s freedom. Tosca fights off Scarpia and prays to God for help. But, eventually, she agrees to Scarpia’s demands in exchange for a mock execution and a safe conduct pass for her and Cavaradossi. After he has written the pass, Tosca stabs Scarpia and rejoices in his death.
ACT III
Before dawn, on the roof of the Castel Sant’Angelo, Cavaradossi writes of his love for Tosca. Tosca arrives at the prison with the safe conduct letter and tells Cavaradossi how she killed Scarpia. She then instructs him to feign death before the execution squad. The soldiers come; they shoot; Cavaradossi falls. Tosca waits until the soldiers leave, rushes to Cavaradossi and finds that Scarpia has thwarted her. The bullets were real and Cavaradossi is dead. The police arrive to arrest Tosca for Scarpia’s murder. She mounts the parapet and cries, “Scarpia, we will meet before God” and plunges to her death.