Act I

The Church of Sant’Andrea della Valle

Angelotti, an escaped political prisoner, looks for the key and clothes his sister has hidden in a chapel. He hides when he hears the Sacristan coming. The artist Cavaradossi arrives and the Sacristan recognises in the Mary Magdalene he is painting a woman who has been coming to the Church to pray. Cavaradossi thinks of the singer Floria Tosca, with whom he is in love.

Angelotti approaches Cavaradossi, who shares his politics, but their conversation is interrupted by Tosca’s arrival. She is jealous – not least when she recognises the woman in Cavaradossi’s painting as the Marchesa Attavanti – but Cavaradossi reassures her, promising to change the eyes in the portrait to Tosca’s.

Returning to Angelotti, Cavaradossi says he will take the fugitive to his house. In case of danger, Angelotti should hide in the well in the garden. They leave as the Sacristan reappears, summoning his choristers. Their high spirits are interrupted by the chief of police, Scarpia, who is searching for the escaped prisoner. He suspects Cavaradossi of harbouring the fugitive, and when Tosca reappears he deliberately inflames her jealousy. When she goes to confront her lover, he has her followed. As the Te Deum is sung, Scarpia gloats that he will destroy Cavaradossi and possess Tosca.

Act II

Scarpia’s residence

Spoletta arrives to tell Scarpia that they have not found Angelotti, but have arrested Cavaradossi. Tosca can be heard singing at a private performance nearby, after which Scarpia has summoned her to join him. Cavaradossi refuses to reveal Angelotti’s hiding place, but the terrible sounds of his torture impel Tosca to tell Scarpia to look in the well.

Cavaradossi is brought in, and is horrified to learn from Scarpia of Tosca’s betrayal. As Scarpia dispatches his men to arrest Angelotti, word arrives that Napoleon has been victorious in battle, and Cavaradossi delights at the news as he is taken away to prison.

Scarpia offers Tosca a bargain – he will spare Cavaradossi’s life if she gives herself to him. Spoletta brings word that Angelotti swallowed poison rather than be arrested, and he waits for instructions about Cavaradossi. Tosca nods to Scarpia, and he apparently gives the orders for a mock execution. Tosca demands a safe conduct; as soon as Scarpia signs it, she stabs him with his own knife.

Act III

The Castel Sant’Angelo at dawn

Cavaradossi is brought in for execution, and bribes the jailer to deliver a farewell letter to Tosca. Left alone, he thinks of his life and love. Tosca arrives in haste, shows the safe passage, and prepares Cavaradossi for the mock execution. When the soldiers fire, Cavaradossi falls dead – Scarpia has tricked them.

Tosca eludes the soldiers pursuing her for Scarpia’s murder by jumping to her death.