While a storm rages, the people of Cyprus await the arrival of Otello, their leader. Roderigo confides to Iago, Otello’s ensign, that he is in love with Desdemona, Otello’s wife; Iago assures Roderigo that Desdemona will soon tire of her husband. Iago orchestrates a fight between Cassio, Otello’s Captain, and Roderigo; the conflict soon escalates to a general riot. Otello, furious, demotes Cassio. As the people disperse and the storm clears, Otello and Desdemona sing of their love.
Iago encourages Cassio to ask Desdemona to intercede for his pardon and reinstatement. As Cassio approaches Desdemona, Iago, aside, articulates his own misanthropic beliefs. When Otello glimpses Cassio with his wife, Iago fans the flames of his jealousy. People of the island surround Desdemona, praising her beauty and purity; but Otello begins to be undone with jealous doubt. Desdemona asks Otello to pardon Cassio and he responds in anger. Emila, Iago’s wife, retrieves a handkerchief of Desdemona’s after it is cast aside. Iago obtains the handkerchief and later describes it to Otello, telling him he saw it in Cassio’s hand.
Desdemona again brings forward Cassio’s case. Otello demands she produce the handkerchief described by Iago. When she cannot, he accuses her of being unchaste, and her denials only feed his fury. While Otello watches, Iago leads Cassio to produce Desdemona’s handkerchief, which Iago had planted in his room. Based on this “evidence” of Desdemona’s unfaithfulness, Iago advises Otello to strangle her; he also pledges to take care of Cassio. In return, Otello names Iago his new Captain.
Desdemona, preparing for bed, is seized with foreboding. After Emilia leaves her alone, Otello confronts his wife, who protests her innocence, but then starts when her husband tells her Cassio is already dead. Taking her reaction as proof of her guilt, Otello smothers Desdemona. Emilia arrives with the news that Cassio has killed Roderigo. The dying Desdemona protests her unjust accusation; as others enter the room and begin saying what they know, it becomes clear to Otello that he was tricked by Iago. In despair and remorse, Otello stabs himself and dies beside Desdemona’s body.