La Muette de Portici or Masaniello or the dumb girl of Portici
The opera is set in Naples in 1647 at the time of Masaniello's revolt against Spanish rule.
ACT ONE
As Alfonso, the son of the Spanish viceroy, marries Elvire, a Spanish princess, he is denounced by Fenella, dumb girl, as her seducer.
ACT TWO
At Portici, Masaniello, Fenella's brother, gives the signal for insurrection.
ACT THREE
They take the rebellion to Naples.
ACT FOUR
In their flight Alfonso and Elvire are unknowingly sheltered by Masaniello himself.
ACT FIVE
Masaniello is eventually killed after saving his royal guests. At the final curtain Fenella leaps into the crater of Vesuvius.

Alfonso, son of the Duke of Arcos, is in love with Fenela, sister of Masaniello, a fisherman. The Duke imprisons Fenela and compels Alfonso to marry a lady of rank. Fenela escapes from her cell, and her brother rouses the people to revolt. Alfonso and his bride, fleeing from the wrath of the mob, are given shelter by Fenela, on account of which her brother is accused of treachery and destroyed by the revolutionists. The death of her brother is too much for Fenela's anguished mind, and she loses her reason and is stricken mute. She is seen wandering around the lava beds of Mr. Vesuvius, in the crater of which she finally hurls herself.