The Duke and members of the Senate discuss news that the Turks have launched a fleet to attack Venetian-controlled Cyprus. Brabantio accuses Othello of using witchcraft to ensnare his daughter. Othello describes their courtship; Desdemona is sent for and confirms that she freely gave her heart to Othello. Brabantio accepts her decision. The Duke sends Othello to defend Cyprus, and Desdemona asks to accompany Othello on his campaign. Othello entrusts her care to Iago and his wife, Emilia. As Roderigo despairs over the loss of Desdemona, Iago advises him to follow her to Cyprus, promising that her love for Othello will not last long. Iago plots to poison Othello’s marriage with jealousy in part because of his suspicions that Emilia has been unfaithful with Othello.
A storm off the coast of Cyprus destroys the Turkish fleet, ending the attack. The Venetian’s ships are delayed by the storm but arrive safely. Iago pulls Roderigo aside and tells him that Desdemona is in love with Cassio. He convinces Roderigo to start a fight with Cassio that evening to discredit his rival. During the celebration of the defeat of the Turks, Iago gets Cassio drunk and Roderigo attacks him. Montano, an official in Cyprus, is wounded by Cassio when he intervenes. Othello enters and demands to know who began the fray. Pretending reluctance, Iago blames Cassio for the violence. Othello dismisses Cassio as his lieutenant. Iago advises Cassio to plead his case to Desdemona who will be able to convince Othello to reinstate him, though Iago plans to make Othello think Desdemona pleads out of love for Cassio.
Emilia and Desdemona listen to Cassio’s suit. Cassio departs abruptly at the sight of Othello and Iago, which Iago hints is cause for suspicion. Desdemona entreats
Othello to reconcile with Cassio. After Desdemona leaves, Iago continues to plant seeds of doubt in Othello’s mind about her and his former lieutenant. Othello demands proof of his wife’s infidelity. Emilia finds Desdemona’s handkerchief and gives it to Iago, who plans to leave it in Cassio’s lodging. Iago then tells Othello that he heard Cassio declaring his love for Desdemona in his sleep. Othello is convinced of her guilt, flies into a rage, and asks Iago to kill Cassio. Iago agrees, and Othello makes Iago his lieutenant.
Desdemona cannot produce the handkerchief when the angry Othello demands to see it. Later, Cassio meets Bianca, his courtesan lover, and asks her to copy the embroidery of a handkerchief he found in his room. Iago tells Othello that Cassio has confessed to infidelity with Desdemona. Othello, overcome with passion, falls into a trance. Later he listens to a conference between Iago and Cassio. Iago asks Cassio about Bianca, and Othello hears only Cassio’s smug laughter. Bianca arrives and returns the handkerchief to Cassio; Othello recognizes the token and reaffirms his desire to see both Desdemona and Cassio dead.
Othello questions Emilia about his wife’s infidelity. She insists that Desdemona is chaste, but Othello refuses to believe her. Roderigo seeks out Iago in desperation and Iago convinces him that he will win Desdemona if he kills Cassio that night. Othello orders Desdemona to prepare for bed and dismiss Emilia; Desdemona obeys. Roderigo ambushes Cassio, and Cassio injures him. Iago stabs Cassio in the leg and flees. While Lodovico and Gratiano tend to Cassio, Iago returns and kills Roderigo. Iago sends Emilia to alert Othello.
Othello enters Desdemona’s sleeping chamber. She wakes to his accusations of infidelity, denies the charge, and pleads for her life. Othello smothers her and Emilia enters to discover her mistress murdered. Montano, Gratiano, and Iago hear Emilia’s cries for help and enter the chamber. Othello cites the handkerchief as evidence and Emilia reveals Iago’s lies. Iago kills his wife and flees, but is captured and returned to the room with the injured Cassio. Othello wounds Iago, then asks for Cassio’s forgiveness. Iago is turned over to the state for torture. Asking the statesmen to report his tragic story justly, Othello stabs himself and dies on the bed with his wife.