The late 1940’s and the world is at war
Act 1 A church
Angelotti, an escaped political prisoner and the former Consul of the Republic, rushes into the church looking for a key which his sister, the Marchesa Attavanti, has left to the Attavanti chapel. As Angelotti hides, the Sacristan enters cleaning the painter Cavaradossi‘s brushes. He is surprised to find the church empty and wonders where Cavaradossi has gone.
Cavaradossi enters interrupting the Sacristan who notices that Cavaradossi’s portrait of Mary Magdalene resembles the Marchesa Attavanti whom Cavaradossi has seen praying but did not know. Taking out a photograph of his lover the diva Tosca, he compares her darker beauty with that of the blonde Magdalene. The Sacristan complains there are too many rivals to the Madonna and leaves.
Angelotti appears from his hiding place though Cavaradossi does not recognise him at first. When he does, he offers him food and hurries him back into the chapel as Tosca is heard calling outside.
Tosca suspects Cavaradossi has been talking to another woman and is jealous. Just as he has calmed her down, she too notices the resemblance to the Marchesa Attavanti in his painting and she doubts him again. Cavaradossi reassures her she is his only love. Tosca leaves, having arranged to meet her lover later that night after she has sung in an opera.
Cavaradossi summons Angelotti from the chapel just as a cannon signals that the police have discovered his escape. To ensure Angelotti’s safety, Cavarodossi accompanies him to his villa. As the choir enters the church, the Sacristan tells them that Umberto II has been beaten at Marengo, and that they will join in a celebration concert that night at which Tosca will sing a new cantata.
Their excitement is silenced by the entrance of Scarpia, chief of police, in search of Angelotti. When Tosca returns to tell her lover she is unable to meet him later that night because of the command performance, Scarpia inflames her jealousy by claiming he has found a fan belonging to Marchesa Attavanti next to Cavaradossi’s easel. Tosca vows vengeance and leaves intent on finding Cavaradossi with his new lover. Scarpia orders Spoletta to follow Tosca. Proud of his scheming, Scarpia joins in the Te Deum.
Act 2 Scarpia's office
Scarpia is convinced that Tosca will, like a falcon, lead his men to Cavaradossi and Angelotti. Intent on conquest, he asks Sciarrone to deliver a note for Tosca when she arrives for the concert, asking her to visit him when it is over.
Spoletta arrives and admits that they could not find Angelotti at Cavaradossi’s villa, but has arrested Cavaradossi. Scarpia demands to see him. Through the open window, Tosca’s voice is heard singing at the concert below. Cavaradossi refuses to admit he has helped Angelotti to escape.
Tosca arrives just before Cavaradossi is led to an ante room and runs to embrace her lover. He whispers to Tosca to keep silent about what she had seen at his villa earlier. Tosca is forced to hear Cavaradossi’s cries of pain. Unable to bear it any longer, she reveals Angelotti’s hiding place. Scarpia orders the torture to stop, and Cavaradossi is brought in bleeding and faint. Just as Tosca assures Cavaradossi she has kept silent, Scarpia orders Spoletta to search in the well in the garden of Cavaradossi’s villa. Cavaradossi turns on Tosca.
Sciarrone rushes in with the news that Umberto II has triumphed at Marengo. Cavaradossi is wildly excited and tells Scarpia his doom is near. Cavaradossi is dragged away and Tosca is left distraught.
Scarpia invites Tosca to sit and join him for supper. When she asks the cost of Cavaradossi’s life, Scarpia says he doesn’t want money, but wants her. She is disgusted. Spoletta enters and explains that Angelotti swallowed poison when they found him. Scarpia orders that his corpse be hung on the gallows and says that the same fate awaits Cavaradossi. Tosca is broken and promises to give herself to Scarpia in exchange for her lover’s freedom. Scarpia says he cannot release Cavaradossi openly to allow the lovers to escape abroad; it must appear that he has been killed. He orders Spoletta to arrange a mock execution ‘as with Count Palmieri’.
Tosca demands that Scarpia writes a letter of safe conduct for herself and Cavaradossi. While Scarpia signs the document, she notices a knife on the table. She hides it behind her back. As Scarpia tries to embrace Tosca, she stabs him in his breast - ‘the kiss of Tosca’. Tosca wipes the blood from her hands and removes the safe conduct letter from the dead man’s fist.
Act 3 A Prison Cell
It is just before dawn and church bells sound for matins. A woman walks the streets near the prison. Cavaradossi enters his cell.
He bribes Sciarrone to convey a farewell note to Tosca and then weeps in despair. Tosca arrives, shows Cavaradossi the safe conduct Scarpia has signed and tells him of how she has stabbed Scarpia. Cavaradossi caresses the hands that committed murder for his sake. Tosca reassures him that the execution will only be a pretence and afterwards they will be free to go abroad. They come together and proclaim the triumph of their love.
Sciarrone arrives. Tosca coaches Cavaradossi on how to fake his death convincingly. A shot rings out and Cavaradossi falls. Tosca admires his performance and waits impatiently for the police to leave. She runs to Cavaradossi and finds he is really dead. As she throws herself on Cavaradossi’s body, she hears voices approaching announcing the discovery of Scarpia’s murder. Spoletta arrives to arrest Tosca who cries ‘Scarpia, before God we meet.’