Tosca is a melodrama in three acts with a libretto by Giuseppe Giacosa and Luigi Illica, after Victorien Sardou’s play La Tosca. Named for a singer around whom the events of the opera proceed, Tosca tells the tale of an escaped prisoner, doomed lovers, and a jealous Chief of Police.
The opera begins with Angelotti, who has just escaped from prison, hiding in the large church in Rome. Cavaradossi arrives to finish his portrait of the Magdalen, which is influenced by the likeness of his beloved Tosca and another woman he has seen in prayer at church. A Sacristan complains of Cavaradossi. Angelotti emerges from hiding and explains to Cavaradossi that he has escaped from the Castel Sant’Angelo, where he had been imprisoned by the order of the Baron Scarpia.
Tosca’s voice is heard and Angelotti returns to hiding. Tosca enters and tells of her jealousy of Marchesa Attavanti (Angelotti’s sister). She suspects that her lover Cavaradossi harbors secret affections for Marchesa Attavanti. Despite her jealousy, Tosca agrees to meet Cavaradossi at his villa after her performance that evening
Tosca leaves. While Cavaradossi and Angelotti plot Angelotti’s escape, they hear a cannon shot from the Castel Sant’Angelo, which indicates that Angelotti’s flight has been discovered. At the same time, the Sacristan returns with the (ultimately false) news that Napoleon has been defeated at Marengo and there is a celebration in the church. Scarpia appears with his agents, searching for Angelotti. Suspicion falls on Cavaradossi after Scarpia finds clues that Angelotti has been in the chapel. Tosca returns and Scarpia arouses further jealousy in her by insisting one of the clues—a fan found in the chapel—belongs to Marchesa Attavanti. After Tosca leaves suddenly, Scarpia orders that she should be followed. He gloats of the possibility that he could capture the fugitive and win the favors of Tosca.
Act 2 beings in Scarpia’s apartment where he eats alone while Queen Carolina entertains downstairs. Cavaradossi has been arrested and is interrogated. Tosca, who had been singing for the Queen, enters while Cavaradossi is being tortured in the next room. Tosca refuses to tell of Angelotti’s whereabouts but the sounds of Cavaradossi being tortured cause her to give away Angelotti’s hiding place in a garden well. Scarpia stops the torture and Sciarrone enters with the news that the Battle of Marengo had been won by Napoleon.
Scarpia declares that Cavaradossi is to be shot at dawn, but he offers to release Cavaradossi if Tosca will give in to his demands. Spoletta then enters with the news that Angelotti has killed himself. Tosca accepts Scarpia’s terms and he decides that Cavaradossi will be given a mock execution. Tosca asserts that Scarpia write her and Cavaradossi a safe-conduct. Just as he finishes doing so, Tosca stabs him and flees.
At the Castel Sant’Angelo, Cavaradossi prepares to die. Tosca enters and explains that there will be a mock-execution, after which they can escape together. However, Scarpia has his revenge posthumously, as his orders did not insure a mock execution and Cavaradossi is shot. Meanwhile, the news of Scarpia’s murder has reached Spoletta, Sciarrone, and other police. They call for Tosca’s blood. Tosca climbs on to the battlements, and crying that she and Scarpia will meet before God, leaps to her death.