Othello, a Moorish general in Venice, has just eloped with a noblewoman, Desdemona. The play opens with Roderigo, one of Desdemona’s former suitors, speaking with Iago, Othello’s subordinate.

Iago hates Othello for promoting another soldier, Cassio, to the rank of lieutenant instead of himself, and Roderigo is angry that Desdemona has married Othello. Together, they go to the house of Desdemona’s father, Brabantio, in an attempt to turn Desdemona’s family against Othello. They tell Brabantio about the elopement, and Brabantio gathers a group of men to find and apprehend Othello and annul the marriage.

When Brabantio finds Othello, Othello has just been called upon by the Duke of Venice. Othello suggests that they all go to the Duke together. That way, Othello is able to answer the summons, and the duke can adjudicate the dispute between Othello and Brabantio.

At the Duke’s court, it is revealed that several Turkish ships are approaching the island of Cyprus, and the Duke of Venice calls upon Othello for military help. Brabantio airs his grievances to the Duke, namely that Othello has run off with his daughter.

Othello defends himself, explaining how he and Desdemona fell in love. They also fetch Desdemona, who corroborates Othello’s story, and Brabantio eventually gives a reluctant blessing to the marriage. Othello sails for Cyprus immediately, followed by Cassio on another ship and Iago, Roderigo, Desdemona, and Emilia (Desdemona’s attendant and Iago’s wife) on yet another ship.

Eventually, they all come together in Cyprus and learn that the Turkish fleet has been scattered by bad weather. Othello throws a party to celebrate the victory and his marriage. Iago, however, plots against Othello and Cassio, convincing Roderigo that Cassio will be another hurdle to reaching Desdemona.

Iago gets Cassio drunk during the festivities, and Roderigo goads him into becoming violent. Montano, the governor of Cyprus, attempts to restrain Cassio, but Cassio attacks him, leaving him wounded. Given Cassio’s brazen actions, Othello has no choice but to demote him from the rank of lieutenant. Iago, seeing an opportunity, suggests that Cassio speak to Desdemona, as she might be able to change her husband’s mind.

Cassio takes Iago’s advice, and upon speaking with her, he learns that Desdemona has already started defending him to her husband. As Desdemona and Cassio discuss how he might be reinstated, Othello sees them speaking with one another. Later, Iago insinuates to Othello that Desdemona and Cassio may be having an affair.

Othello does not want to believe this, but Iago reminds Othello that their marriage is based on a lie (elopement), and thus it is feasible that Desdemona may lie again. Knowing that Desdemona will be speaking favorably about Cassio in an attempt to reinstate him, Iago tells Othello to be vigilant and note if Desdemona starts talking about Cassio more favorably than usual. Othello soon begins to suspect his wife of sleeping with Cassio.

Shortly thereafter, Desdemona, Emilia, and Othello are together, and Othello complains of a headache. Desdemona attempts to wrap his head in a handkerchief that he gave her while they were still courting, but it falls to the floor, and Emilia picks it up. She delivers the handkerchief to Iago, who has asked Emilia to obtain it on several occasions.

Iago plants the handkerchief in Cassio’s room. Othello later approaches Iago and requests proof of his wife’s infidelity. Iago tells Othello that Cassio has been talking about Desdemona in his sleep and that Desdemona has given her handkerchief to Cassio. In light of this, Othello promotes Iago and asks him to kill Cassio.

In his next interaction with Desdemona, Othello asks her what has happened to the handkerchief he gave her, telling her that it was a magical family heirloom. It is lost, but she does not reveal this to Othello, claiming instead to have it in her room. As he continues to demand that she produce the handkerchief, she tries to turn the conversation to Cassio, which infuriates Othello even more.

After the altercation, Desdemona tells Cassio that she will speak more to her husband when he is in better spirits. When Cassio is alone, Bianca, a prostitute whom he frequents, comes to speak with him. She is in love with him and wants to have dinner with him. Instead, he sends her off to make a copy of the handkerchief he found in his room because he likes the design, but he knows he will have to find the owner and eventually return it.

Iago, attempting to “prove” Cassio’s guilt, speaks with Cassio while Othello hides and watches. Iago has told Othello that he is going to speak to Cassio about his affair with Desdemona, but Iago actually asks about his last encounter with Bianca. Othello cannot hear most of the conversation but believes that Cassio is speaking about sleeping with Desdemona.

At that moment, Bianca bursts in with the handkerchief and refuses to help Cassio copy it because she believes that it is a token of love from another woman. Cassio chases after Bianca, and Othello comes out of hiding, convinced that Cassio and Desdemona are having an affair.

He begins contemplating killing Desdemona, but she and Lodovico enter with news that they are to appoint Cassio as governor of Cyprus and return to Venice. Desdemona is pleased with this information, but Othello strikes her and storms off.

Meanwhile, Roderigo is angry because he is no closer to wooing Desdemona, and he tells Iago that he is going to be honest with her. Iago, however, lies and convinces him that Othello and Desdemona are going to Africa. The only way to keep them in Cyprus is to kill Cassio.

In the final act of the play, Roderigo attacks Cassio and attempts to kill him, but Cassio wounds Roderigo instead. In the confusion, Iago comes out of hiding, injures Cassio’s leg, and kills Roderigo for fear that Roderigo could implicate him. Bianca enters and attempts to comfort Cassio, but Iago accuses Bianca of masterminding the attack.

Meanwhile, Othello enters his bedchamber, committed to strangling his wife. He kisses her and she wakes, but he explains that he must kill her, despite her protests and claims of innocence. As she attempts to fight back, he forces her to the bed and smothers her to death.

Emilia enters to tell Othello about the attack on Cassio but discovers that he has killed Desdemona. Othello explains that Iago caught Desdemona and Cassio sleeping together, but Emilia, in shock, explains his mistake.

Cassio, Lodovico, and Gratiano enter with Iago in custody, explaining that they found letters on Roderigo’s body implicating him in the attack against Cassio. Emilia also explains that she stole the handkerchief for Iago.

Othello stabs Iago, and Iago kills Emilia for betraying him. Othello, realizing his mistake, then kills himself, and the men haul Iago off to punish him for his deception.