On the Island of Cyprus, Venetian officers and the Cypriot townspeople anxiously await the arrival of their commander, the Moor, Otello, whose ship is battling a violent storm. The storm subsides and Otello lands, to the joy of the crowd. Only Iago and Roderigo do not share the general happiness. Iago is bitter because Otello has appointed Cassio, not him, as his lieutenant, and Roderigo is unhappy because he is in love with Desdemona, Otello’s wife. Iago plots his revenge.
When Cassio appears, Iago and Roderigo encourage him to drink. Roderigo provokes a duel with the drunken Cassio, who accidentally wounds Montano when he tries to separate them. Otello, summoned by the brawling, dismisses Cassio from his service. Desdemona also arrives, and when all have gone, she and Otello again declare their love.
However, Cassio does not have obtained his master's forgiveness. Iago, now Otello’s confidant, continues his plotting. He advises Cassio to ask Desdemona to intercede with Otello for his pardon.
The Moor sees Cassio with his wife, and Iago plants the seeds of jealousy, which grow as Desdemona pleads with her husband to forgive their old friend.
Iago takes one of Desdemona’s handkerchiefs to use as evidence of her infidelity. When he and Otello are alone, Iago reports that he heard Cassio talk in his sleep about Desdemona as if they were lovers. Otello vows vengeance and Iago swears to assist him and to furnish him with proof.
In the hall of the royal castle.
Otello asks Desdemona about the handkerchief he gave her as a proof of his pure love. She does not remember where it was left and Otello openly accuses her of adultery.
Later Iago tell Otello to spy him on a meeting with Cassio, who displays a story about an adventure with a girl and about handkerchief he has mysteriously found in his room. It is Desdemona’s, placed there by Iago. Otello cannot hear the two men’s words, but the sight of the handkerchief convinces him.
When he receives the ambassadors, Otello cannot restrain his jealous fury and, in front of all, insults his wife and hurls her to the floor. Iago feels that his triumph is near. In the up-coming night, Roderigo will kill Cassio and Desdemona.
Desdemona prays and goes to bed. Otello enters and warns her that he has come to kill her. Again she protests her innocence, but he refuses to believe her and strangles her, the last words being “I am innocent”. Desdemona’s companion Emilia knocks and then bursts in to tell Otello that Roderigo, who according to Iago’s plot was to kill Cassio, has himself been killed.
When Desdemona moans Emilia cries out in horror and others gather, including Iago, whose villainy is revealed. Otello orders the arrest of Iago and taking the knife kills himself over Desdemona’s lifeless body.