Fidelio (originally named Leonore, oder Der Triumph der ehelichen Liebe; English: Leonore, or The Triumph of Married Love), Opus 72, is a German opera with spoken dialogue by Ludwig van Beethoven, his only opera.
Florestan is alone in his cell, deep inside the dungeons. He sings first of his trust in God, then has a vision of Leonore coming to save him ("Gott! Welch Dunkel hier!" [God! What darkness here]... "In des Lebens Frühlingstagen" [In the spring days of life]). He collapses and falls asleep. Rocco and Leonore come to dig his grave and find him asleep. As they dig Rocco urges Leonore to hurry ("Wie kalt ist es in diesem unterirdischen Gewölbe!" [How cold it is in this underground chamber] ... "Nur hurtig fort, nur frisch gegraben" [Come get to work and dig!]). This is the Gravedigging Duet.
Florestan awakes and Leonore recognizes him. When Florestan learns at last that he is in Pizarro's prison, he asks that a message be sent to his wife, Leonore Florestan, but Rocco says it is impossible. Florestan begs for a drop to drink, and Rocco tells Leonore to give him one. Florestan does not recognize Leonore but tells her she will be rewarded in Heaven ("Euch werde Lohn in bessern Welten" [You shall be rewarded in better worlds]). She begs Rocco to be allowed to give Florestan a crust of bread, and he agrees. Florestan eats.
Rocco obeys his orders and sounds the alarm for Pizarro, who appears and asks if all is ready. Rocco says that it is and tells Leonore to leave, but instead she hides. Pizarro reveals his identity to Florestan, who accuses him of murder ("Er sterbe! Doch er soll erst wissen" [Let him die! But first he should know]). As Pizarro brandishes a dagger, Leonore leaps between him and Florestan and reveals her identity. Pizarro raises his dagger to kill her but she pulls a gun and threatens to shoot him.
Just then the trumpet is heard, announcing the arrival of the minister. Jaquino enters, followed by soldiers, to announce that the minister is waiting at the gate. Rocco tells the soldiers to escort Governor Pizarro upstairs. Florestan and Leonore sing to their victory as Pizarro declares he will have revenge, and Rocco expresses his fear of what is to come ("Es schlägt der Rache Stunde" [Revenge's bell tolls]). Together, Florestan and Leonore sing a love duet ("O namenlose Freude!" [O unnamed joy!]).
The prisoners and townsfolk sing to the day and hour of justice which has come ("Heil sei dem Tag!" [Hail to the day!]). The minister, Don Fernando, announces that tyranny has ended. Rocco enters, with Leonore and Florestan, and he asks Don Fernando to help them ("Wohlan, so helfet! Helft den Armen!" [So help! Help the poor ones!]). Rocco explains how Leonore disguised herself as Fidelio to save her husband. Marzelline is shocked. Rocco describes Pizarro's murder plot, and Pizarro is led away to prison. Florestan is released from his chains by Leonore, and the crowd sings the praises of Leonore, the loyal savior of her husband ("Wer ein holdes Weib errungen" [Who has got a good wife]).