Zelmira, a dramma in two acts to a libretto by Andrea Leone Tottola, was first performed at Teatro San Carlo, Naples, on 16th February 1822.
The singers in the first performances were Antonio Ambrosi (Polidoro), Isabella Colbran (Zelmira), Giovanni David (Ilo), Andrea Nozzari (Antenore), Anna Maria Cecconi (Emma), Michele Benedetti (Leucippo), Gaetano Chizzola (Eacide), Massimo Orlandini (Gran Sacerdote).
The story is taken from Zelmira by Dormont de Belloy (1762).
The scene is laid by the sea, at a short distance from the city walls of Lesbos. The warriors of Mitylene are mourning the tragic death of their leader. Leucippo, pretending to be anxious to avenge Azorre, repeatedly calls aloud for someone to tell him the name of the murderer: the soldiers tell him that they do not know who did it. Supported by the army, Leucippo now proclaims Antenore the successor to Azorre and plots with him to get him crowned King of Lesbos. The only obstacles to their scheme are Zelmira and her small son: the two conspirators decide to blame her for the deaths of both Azorre and her father. Zelmira is now, therefore, forced to try to defend herself from the double accusation of murder and parricide; even her faithful friend Emma is inclined to suspect her until Zelmira takes her down into the vault under the graveyard and proves to her that Polidoro is still alive. Zelmira and Polidoro embrace happily and, fearful of what the future may bring, try to comfort and inspire hope in one another.
Meanwhile, in front of the temple of Jove, the people are acclaiming the victorious Prince Ilo, back from the wars and impatient to be re-united with his beloved wife and son. When husband and wife meet, Zelmira is obviously troubled, but cannot bring herself to tell her husband at once of the terrible accusations that have been made against her. In this way Antenore and Leucippo find it easy to tell Ilo their version of Zelmira's supposed crimes. Zelmira takes her son away from danger and entrusts him to the care of Emma. In the throne room, Antenore is crowned King of Lesbos to the joy of all the people. Whilst Ilo is anxiously looking for his son, Leucippo tries to stab him. Zelmira hurls herself upon the would-be assassin and stays his hand, but Leucippo, slyly turning the occasion to his own advantage, lets her get possession of the dagger and, whilst she is still holding it, warns Ilo that she is about to stab him; in this way Leucippo manages to convince Ilo that his beloved wife, already guilty of murdering Azorre and her own father, was trying to kill him too. Despite her protestations of innocence, Zelmira is led off to prison.
In the throne room of the royal palace, Leucippo gives Antenore a letter of Zelmira's that he has intercepted, in which she explains her innocence to Ilo and implores him to save her. From what she writes in the letter it is easy to guess that Polidoro is still alive: Leucippo therefore suggests that Zelmira be set free in order that they can follow her and see where she goes. Meanwhile, whilst Ilo is lamenting his unhappy marriage outside the walls of Lesbos, he suddenly comes across Polidoro, who reveals the truth about the calumnies that have been invented to harm Zelmira. The two men warmly embrace and, whilst Polidoro returns to the safety of the tombs until such time as the rescue plan can be put into operation, Ilo rushes off to find his wife. Meanwhile Zelmira has been set free of her chains and believes that this must be due to her husband's intervention, and that therefore he must be convinced of her innocence. She discusses the situation with Emma, not knowing that Antenore and Leucippo are listening in to the conversation; the plotters realize that Ilo by now must know the truth and must be preparing to help Polidoro. So the two wicked men, coming out into the open, lay one last trap for Zelmira; pretending that Ilo has already carried off Polidoro to safety, they trick her into inadvertently revealing her father's hiding-place, and so they are able to find and capture him. The unhappy girl courageously and generously offers her own life in place of her father's. When Emma learns that Antenore intends to kill both the prisoners at the earliest opportunity, she rushes off to find Ilo and warn him to hurry up the rescue attempt.
The final scene takes place in the prisons of Lesbos. Zelmira is lamenting her father's and her own unhappy destiny, fearing that her husband has abandoned her. Suddenly the door opens and Antenore and Leucippo come in, intent upon committing their crime. However, a noise is heard offstage of battle-cries and fighting, and heavy blows rain upon the walls. When Antenore attacks Polidoro, Zelmira immediately draws a dagger from her bosom and defends him. At last Ilo enters through a breach made in the wall, brandishing his sword, and he is closely followed by Eacide, his soldiers, the people of Lesbos, Emma and Zelmira's little boy. Antenore and Leucippo are dragged away by the guards, whilst Zelmira is left happily re-united with her dear ones.