Synopsis
Place: Sicily
Time: 13th century
Act 1
Scene 1: The seashore near Caldora Castle

On a stormy sea-shore, fishermen watch a ship foundering in a huge storm. They help the crew come ashore and among the survivors is Gualtiero, who recognises his old tutor Goffredo, now appearing dressed as a hermit. He explains that he has lost everything. Gualtiero tells him that, in spite of his hatred for his persecutor Ernesto, he drew strength from his continuing love for Imogene. (Aria: Nel furor delle tempeste / "In the fury of the storm / in the slaughter of a pirate's life / that adored image appears in my thoughts"). When the fishermen arrive to inform both men that the noble lady who lives close by is coming to help the shipwrecked men, Gualtiero is urged to hide himself since he will be alone among enemies. He enters Goffredo's hut.

It is Imogene who arrives to offer hospitality to the shipwrecked strangers, but Gualtiero does not reveal himself. She tells her companion Adele that she dreamed that he had been killed by her husband. (Aria: Lo sognai ferito, esangue / "My duty is the compassion / that sends me to the aid of strangers"). From what Itulbo has told her about the pirate ship, she assumes that he is dead. When he comes out of the hut, Gualtiero recognises her, but the hermit makes him re-enter. Imogene is urged to return to the castle, but to herself, she imagines that she sees Gualtiero everywhere she looks. (Aria: Sventurata, anch'io deliro / "Hapless one, I too am delirious / obsessed by a vain love").

Scene 2: The Castle terrace at night

At night, Itulbo warns the strangers not to reveal that they are the pirates who have been pursued by Ernesto. Meanwhile, Imogene is strangely fascinated by the mysterious stranger who enters covered in a cloak. He soon reveals to her who he really is. Gualtiero learns that she had married Ernesto only because he had threatened her father's life. (Extended duet, first Gualtiero: Pietosa al padre! e meco / eri si cruda intanto! / "Pity for your father! But you / were so cruel to me! / And I, deceived and blind, lived, / lived for you alone!"; then Imogene: Ah! qui d'un padre antico / tu non tremasti accanto / "Ah, you never trembled / for an aged father). When Imogene's ladies bring her son into the room, he is angry and almost removes his dagger from his belt, before handing the boy back. He then leaves.

Scene 3: The Castle grounds

Ernesto and his men celebrate victory over the pirates (Sì, vincemmo, e il pregio io sento / "Yes, we conquered and I feel proud of such a noble victory"), but he is annoyed that Imogene is not celebrating too. He asks her if she has found out who the shipwrecked men are, telling her that he expects to question the hermit and the man who is described by the hermit as their leader: Itulbo. Itulbo describes himself as being from Liguria and, upon questioning him, Ernesto recognises by his dress and accent that he is not from the local area. He continues to press Itulbo on the whereabouts of Gualtiero, knowing that pirates have come from Ligurian shores; he is reluctant to accept the group until they can provide greater proof of who they are. Meanwhile, they must remain as prisoners. Beginning with a duet, which initially includes Gualtiero, who declares his readiness to fight, Ernesto somewhat suspicious, Imogene and Adele in anguish, then the hermit (Goffredo) and the women, it extends to include all the principals who express their conflicting emotions, though the hermit manages to restrain Gualtiero from giving his identity away.

Act 2
Scene 1: The entrance to Imogene's apartments

Adele tells Imogene that Gualtiero wishes to see her before he leaves. She is reluctant, but she recognises that she must do it. As she is about to leave, Ernesto arrives and accuses Imogene of being unfaithful to him: (Ernesto, aria: Arresta / Ognor mi fuggi / "Stay! You continually avoid me! Now the time has come for me to have you at my side"; then duet.) She defends herself by saying that her continuing love for Gualtiero is based solely on her remembrance of their past encounters. Ernesto is inclined to take her word for it, but, when a message is delivered in which he is told that Gualtiero is being sheltered in his own castle, he is consumed by rage, demands to know where his enemy is, and then storms out. Imogene follows.

Scene 2: The Castle terrace
Gualtiero and Itulbo meet on the terrace at daybreak, the latter encouraging him to flee with all his men. But Gualtiero stands firm and, as Itulbo leaves, Imogene comes onto the terrace. She urges him to be brief, to leave immediately, but he tries to comfort her before they part (Aria: Per noi tranquillo un porto / l'immenso mare avrà / "For us the vast sea / will have a calm port") at the same time as he urges her to come with him to the safety of one of his two ships which have arrived. But she tries to leave, encouraging him to forgive and forget. Their acceptance of the situation alternates with passionate declarations of love, and Ernesto, arriving, conceals himself and overhears the end of their duet. As the couple part, Ernesto reveals himself, but Imogene rushes between them, trying to convince Gualtiero to flee. Defiant, he ignores her, proclaiming to Ernesto that his thirst for his blood has not diminished over ten years. The two men demand blood and, in a trio finale as they exit, they continue in this vein while Imogene pleads that they kill her. The two men depart to fight, and Imogene follows.

Scene 3: The courtyard of the Castle

A funeral march is heard as Ernesto's knights enter followed by Adele and the ladies. All grieve over Ernesto's death at the hands of "a traitor, a vile pirate". Gualtiero, to the amazement of Ernesto's retainers, gives himself up to the knights and, as he is taken away, he prays that Imogene may forgive him (Tu vedrai la sventurata / "You will see the unhappy lady / whom I caused so many tears / and tell her if I wronged her / I also knew how to avenge her"). She appears in a state of anguish and sees visions of her dead husband and her son (Col sorriso d'innocenza ... Oh sole, ti vela di tenebre oscure / "With the smile of innocence / with the glance of love / pray speak to your father of clemency and pardon"). Meanwhile, from the Council chamber, the Knights condemn Gualtiero to death and, as the scaffold is erected, Imogene is raving: (Finale: Oh, sole! ti vela / "Oh sun, veil yourself / in darkest gloom / hide the cruel axe / from my sight"). Her ladies lead Imogene from the courtyard.