This article: Scarpia's apartment in the Palazzo Farnese, that evening
Scarpia, at supper, sends a note to Tosca asking her to come to his apartment, anticipating that two of his goals will soon be fulfilled at once. His agent, Spoletta, arrives to report that Angelotti remains at large, but Cavaradossi has been arrested for questioning.  He is brought in, and an interrogation ensues. As the painter steadfastly denies knowing anything about Angelotti's escape, Tosca's voice is heard singing a celebratory cantata elsewhere in the Palace.
She enters the apartment in time to see Cavaradossi being escorted to an antechamber. All he has time to say is that she mustn't tell them anything.  Scarpia then claims she can save her lover from indescribable pain if she reveals Angelotti's hiding place. She resists, but the sound of screams coming through the door eventually breaks her down, and she tells Scarpia to search the well in the garden of Cavaradossi's villa.
Scarpia orders his torturers to cease, and the bloodied painter is dragged back in. He's devastated to discover that Tosca has betrayed his friend. Sciarrone, another agent, then enters with news: there was an upset on the battlefield at Marengo, and the French are marching on Rome. Cavaradossi, unable to contain himself, gloats to Scarpia that his rule of terror will soon be at an end. This is enough for the police to consider him guilty, and they haul him away to be shot.
Scarpia, now alone with Tosca, proposes a bargain: if she gives herself to him, Cavaradossi will be freed. She is revolted, and repeatedly rejects his advances, but she hears the drums outside announcing an execution. As Scarpia awaits her decision, she prays, asking why God has abandoned her in her hour of need: "Vissi d'arte" ("I lived for art"). She tries to offer money, but Scarpia isn't interested in that kind of bribe: he wants Tosca herself.
Spoletta returns with the news that Angelotti has killed himself upon discovery, and that everything is in place for Cavaradossi's execution. Scarpia... contains an answer for the question: What is the name of the person from whose pocket she removes the safe-conduct, then lights candles in a gesture of piety, and places a crucifix on his body before leaving?, what is it ?


Scarpia