Act I
Morning. The Church of Sant’Andrea della Valle in Rome.
Cesare Angelotti, a political prisoner, has escaped from the Castel Sant’Angelo. He finds refuge in the Attavanti family chapel, using a key hidden in the church by his sister, the Marchesa Attavanti. As the Sacristan kneels in prayer for the Angelus, Mario Cavaradossi arrives to continue work on a painting of Mary Magdalene. The picture, he admits, has been inspired both by his mistress, the singer Floria Tosca, and by a young woman he has seen at prayer in the church. As the Sacristan leaves, Angelotti emerges. Cavaradossi recognises him and promises to help. Hearing Tosca’s voice outside, he gives Angelotti a basket of food and hurries him into hiding once more. Tosca, however, has heard their voices in the church; when she finds Mario alone, her jealousy is aroused. Cavaradossi soothes her, until she sees the Magdalene portrait. Cavaradossi calms her: they agree to meet later. Angelotti emerges from hiding as the prison cannon announces that his escape has been discovered. Cavaradossi escorts him to safety. The Sacristan returns: a great political victory has been won, a Te Deum is to be sung in celebration, and Tosca will perform at the Farnese Palace that evening. The altar boys’ revels end abruptly, however, at the arrival of Baron Scarpia, the Chief of Police, whose men have tracked Angelotti to the church. A search reveals an empty food basket in the Attavanti chapel, together with a fan bearing the family’s crest. Has Cavaradossi, already politically suspect, helped an escaped prisoner? Tosca returns: her performance that evening means she and Mario cannot meet that night. Cavaradossi’s absence arouses her suspicions, further fuelled by Scarpia’s insinuations and his revelation of the Attavanti fan. Tosca rushes away and Scarpia sends his men in pursuit. As the Te Deum reaches its climax, he relishes the thought of victory over both Cavaradossi and Tosca.
Act II
That evening. Scarpia’s apartments at the Farnese Palace.
Scarpia, anticipating success, has sent for Tosca. His assistant, Spoletta, returns: a search of Cavaradossi’s villa has failed to find Angelotti, but Cavaradossi has been arrested in his place. As Tosca’s voice is heard from the concert nearby, Cavaradossi refuses to answer Scarpia’s questions. Frustrated, Scarpia sends him to the torturers. Tosca arrives. Scarpia’s questioning grows more urgent until, hearing Mario’s cries of pain, she reveals Angelotti’s hiding place. Mario is brought in, but his reconciliation with Tosca is short-lived as Scarpia reveals her betrayal. Suddenly Sciarrone enters: news of the political victory was premature – they have suffered a major defeat. Alone with Scarpia, Tosca bargains for Mario’s life. His terms are simple and, when she reluctantly agrees, Scarpia instructs Spoletta to arrange a mock execution at dawn. After that, the lovers will be free to leave with a safe-conduct provided by him. Victorious at last, Scarpia rushes into Tosca’s embrace and finds only death on the blade of a knife.
Act III
Dawn. The Castel Sant’Angelo.
A shepherd boy sings as his flock passes by. As Cavaradossi, having bribed his jailer, writes a last letter to Tosca, his composure breaks down. Suddenly, Tosca arrives, revealing Scarpia’s death and the impending mock execution. Spoletta and the firing squad enter. The lovers are confident – Tosca even instructs Mario how to act – but Scarpia plays the final trick: Mario’s death is for real. As Scarpia’s murder is discovered, Tosca leaps to her own death.