Fidelio is Ludwig van Beethoven's only opera, set in 18th century Spain.
Florestan, a Spanish noble, is a secret captive of Don Pizarro, a cruel prison governor. To free him, his wife Leonore disguises herself as a man (Fidelio) and is hired by Rocco, the jailor at the prison. Marzelline, Rocco’s daughter, falls in love with Fidelio, rejecting the advances of Jaquino, an admirer.
The king’s minister, Don Fernando, suspects the governor of abusing his power and announces an inspection of the prison. Pizarro orders Rocco to kill Florestan, but he refuses. Leonore begs Rocco to take her to the dungeon in search of Florestan.
When Pizarro comes to kill Florestan, Leonore reveals herself, and threatens him with a pistol. Just in time, Don Fernando arrives, arrests Pizzaro and frees all the prisoners. Leonore removes Florestan's chains and is hailed by the crowd as a heroine.
This beautiful quartet conveys four very different perspectives on the situation the characters find themselves in. Marzelline is happily in love; Leonore is acutely aware of the dangers of her disguise; Rocco imagines a happy marriage ahead for his daughter; Jaquino sees his hopes of happiness dashed.