ACT I. Before the palace. Othello, joyfully acclaimed by the people, lands in Cyprus. Iago, who hates Cassius, Othello's lieutenant, because he has been preferred by Othello, and also dislikes the Moor, at first incites Roderigo to gain Desdemona's love, then induces Cassius to drink heavily. The latter, excited by wine, draws his sword against Montano, and is punished by being banished by Othello. Othello takes his wife Desdemona to the palace.
ACT II. A room in the palace. The scene closely follows Shakespeare. Iago first advises Cassius to ask Desdemona to intercede for him, thus bringing about his reinstatement; then he arouses the jealousy of the Moor against his lieutenant. Iago takes from his wife Emilia a handkerchief, which Desdemona has lost, to use as an evidence of her infidelity. Othello and he together swear to be revenged upon Cassius.
ACT III. A room in the palace. Iago brings Cassius to the palace, while Desdemona is interceding for him with Othello. Iago leads in Cassius, after Othello has left the apartment, and arranges the conversation in such a way that the listening Othello becomes furiously jealous. He manages to slip Desdemona's handkerchief into Cassius's hands, then he takes it from him before the eyes of Othello, and gives it to the Moor after Cassius's departure. Othello is now convinced of Desdemona's guilt. When a Venetian delegation announces his degradation from office he beats Desdemona and faints from anger, which arouses the malicious laughter of Iago.
ACT IV. The bedchamber of Desdemona. Awaiting death, Desdemona bids Emilia leave her, and retires. Othello steps to her bedside, awakens her, again becomes furious, and kills her, not with poison, as the villain Iago has counselled, but by throttling her with his own hands. Emilia rushes in, witnesses the dreadful deed, and reveals Iago's treachery, explaining that he has received the handkerchief from her. When the noblemen, aroused by the tumult, enter the chamber, Othello slays himself beside the corpse of Desdemona.
References and external links: Plot taken from The Opera Goer's Complete Guide by Leo Melitz, 1921 version.