ACT I
As a violent storm rages off the coast of the island of Cyprus, its citizens await the return of their Governor, Otello, the Moorish general of the Venetian army.  Otello arrives safely and announces that he has defeated the Turks. ('Esultate!')  Iago, Otello’s ensign, and Rodrigo discuss their unhappiness with the current state of things.  Iago is resentful because Otello had promoted his rival Cassio instead of him, and Rodrigo is unhappy because he is in love with Otello’s new wife Desdemona.  Iago plots his revenge and promises to help Rodrigo at the same time.  Later at a bonfire gathering Iago coerces Cassio to intoxication, toasting Otello and his new bride. ('Inaffia l'ugola!')  He then provokes Rodrigo to duel with the drunken Cassio.  Montano is wounded when he tries to break up the fight and the noise from the brawl brings Otello out of the castle, demanding an explanation.  Iago feigns ignorance and the blame falls on Cassio, who Otello strips of his recent promotion when he sees that the fight has upset Desdemona.  Otello dismisses the crowd and, left alone, Otello and Desdemona declare their love for each other. ('Già nella notte densa')

ACT II
Iago convinces Cassio that he should seek Desdemona’s help in getting his position back, saying that she has influence over her husband.  Left alone, Iago declares his credo that he was created wicked by a cruel god. ('Credo in un Dio crudel') Otello enters and Iago draws his attention to Cassio talking with his wife and plants the seeds of jealousy, which grow when Desdemona later pleads Cassio’s case.  Thinking that his irritation is a sign of illness, Desdemona tries to wipe Otello’s brow, but he throws her handkerchief to the ground.  After Desdemona’s attendant Emilia, who is Iago’s wife, goes to retrieve it, Iago demands that she give him the handkerchief.   After the women leave, Iago further flames Otello’s fury by saying that he has heard Cassio utter Desdemona’s name in his sleep ('Era la notte') and that he has seen Cassio carrying her handkerchief.  Otello vows vengeance and Iago promises that he will help him and find further proof of Desdemona’s infidelity. ('Si, pel ciel marmoreo guiro!')

ACT III
Iago tells Otello that further proof of Desdemona and Cassio’s affair is forthcoming.  Desdemona enters and again pleads that he reinstate Cassio. ('Dio ti giocondi, o sposo') Angered by her insistence on the subject, Otello hints at his suspicions but she fails to understand.  When he demands to see her handkerchief and she again brings up Cassio, he openly accuses her infidelity and calls her a courtesan.  She tearfully declares her innocence but Otello sends her away.  Left alone, Otello rages that he would have preferred that heaven afflict him with anything but this. ('Dio! mi potevi scagliar)' He hides when Iago and Cassio enter.  Iago flashes the handkerchief that he previously stole and leads Cassio into a discussion of his mistress Bianca in such a way that he knows Otello will think they are discussing Desdemona.  As trumpets announce the arrival of a Venetian dignitary, Otello vows to kill his wife that night.  The ambassador Lodovico enters with papers calling Otello back to Venice and naming Cassio as governor.  Otello breaks into rage and throws Desdemona to the ground. ('A terra!. . .si. . .nel livido fango…') As the shocked onlookers try to console her, Otello orders everyone to leave.  Succumbing to his fit of anger, Otello collapses to the floor and Iago gloats over him, ironically calling him the Lion of Venice. ('Ecco il Leone! ...')

ACT IV
As Emilia helps her prepare for bed, Desdemona is filled with foreboding.  She sings a tale of a maiden forsaken by her lover.  ('Mia madre aveva una povera ancella') She bids Emilia farewell and then says her evening prayers before climbing into bed. ('Ave Maria')  Otello sneaks into the room and kisses his sleeping wife.  When she wakes, he tells her to prepare for death.  ('Diceste questa sera le vostre preci?') Despite Desdemona’s adamant declarations of innocence, Otello strangles her.  Emilia knocks with news that Cassio has killed Roderigo in accordance with Iago’s plot.  When she finds the dying Desdemona, Emilia’s cries bring Cassio, Lodovico, and Iago into the room.  When Iago’s treachery is revealed, he is able to escape from the room.  Realizing his horrible mistake, Otello stabs himself and dies over Desdemona’s lifeless body. ('Niun mi tema')