Othello Scene Summaries:
Source: http://www.cliffsnotes.com/WileyCDA/LitNote/id-138.html
See Commentaries 

Act One. Scene One:
On a street in Venice, there is an argument between Roderigo, a nobleman, and Iago, an ancient (captain) in the defense forces. Roderigo, in love with the noble lady Desdemona, has paid large sums of money to Iago, on the understanding that Iago would give her gifts from him and praise him to her. Roderigo hopes to win Desdemona’s love and marry her. However, they now have news that Desdemona has left the house of her father, Brabantio, a Senator, and eloped with Othello, a Moor (an African) who is a General in the defense forces.

Roderigo fears he has lost both his lady and his money. Iago reveals to Roderigo that it is in his (Iago’s) nature to plot and tell lies to get what he wants and that he has a plan. He hates Othello for promoting Cassio to the position of lieutenant, a position that Iago wanted for himself. Iago plans to bring about Othello’s downfall, and Roderigo will have Desdemona. First, they must wake Brabantio and cause an outcry. They bang and shout until Brabantio comes out onto the balcony. Iago tells him in inflammatory words that Desdemona has run away with Othello, and Brabantio, enraged, joins Roderigo to wake the neighbors and organize a search party.

1.2:
Iago warns Othello that there may be a legal attempt to break the marriage, but Othello knows his military worth to Venice and meets the Duke and Senators with confidence. Cassio has been sent to fetch him to an urgent meeting about the situation in Cyprus. Iago tells Cassio of Othello’s marriage. Brabantio’s party arrives; Brabantio threatens Othello with violence and accuses him of using sorcery to seduce Desdemona, his reasoning being that she would never marry Othello voluntarily. Brabantio calls for Othello’s arrest and imprisonment but cedes precedence to the Duke’s summons to the emergency meeting.

1.3:
Several reports have come in from Cyprus, all calling attention to a Turkish fleet that is expected to attack. The reports differ in the size of the fleet, but all speak of the danger as the combined force has turned back toward Cyprus. Othello enters the meeting with Cassio, Brabantio, Iago, and others, and the Duke immediately appoints Othello to lead the forces to defend Cyprus.

At this point, the Duke notices Brabantio, who believes that his daughter has been corrupted with magic potions because, according to him, she wound never willingly marry such a man as she did. Initially, the Duke promises him support in a prosecution for witchcraft, a capital crime, against the man who has seduced his daughter, but when the Duke realizes the seducer is Othello, he calls on the general to defend himself.

Othello describes his courtship of Desdemona in a dignified and persuasive speech (76–93 and 127–169) and asks the Duke to send for Desdemona so that she may speak. Iago leads the group that goes to fetch her. When Othello finishes speaking, the Duke declares in favor of Othello: “I think this tale would win my daughter too” (170). Desdemona then speaks, gently outlining an argument so strong that it finishes the whole debate: She owes obedience and thanks to her father for her upbringing, but now that she is married, her loyalty is to her husband, just as her mother’s loyalty was to Brabantio. Fathers must give way to husbands.

Othello must go immediately to Cyprus to command its defense, and Desdemona requests to go as well. The Duke grants her wish, and Othello, who must leave that night, delegates Iago to follow later in another ship, bringing Desdemona and whatever else is needed. Iago’s wife, Emilia, will look after Desdemona as her maid. As Othello leaves. Brabantio warns Othello, “She has deceived her father, and may thee” (289), but Othello is certain of Desdemona’s faithfulness.

Iago and Roderigo are left on stage. Roderigo is downcast and talks of drowning himself. Iago replies with scorn that such misery is silliness and convinces Roderigo to go to Cyprus and wait for Desdemona to come to him, as she will surely soon become bored with Othello. Iago, because he hates Othello, says he will help Roderigo have Desdemona and reminds Roderigo to bring plenty of money.

Iago, alone on stage, considers the situation: He has consolidated his source of money, and he has heard a rumor that Othello has had sex with his wife, Emilia. Although he does not believe the rumor, he will act as though he does to feed his hatred. Also Iago will aim to get Cassio’s position of lieutenant, which he thinks should have come to him.

Act Two. Scene One:
Act II and all subsequent acts take place in Cyprus, in the Venetian fortifications. Montano, Governor of Cyprus, awaits the arrival of the Venetian forces, delayed by a violent storm at sea. A messenger arrives with news that the Turkish fleet has been so damaged by the storm that it no longer threatens Cyprus. Cassio’s ship, followed by Desdemona’s ship, is the first Venetian ship to arrive. Desdemona’s first question is for news of Othello. The two pass the time, waiting for news, and Iago watches, planning to catch Cassio in his own courtesies.

Othello finally arrives, triumphant, and he, Desdemona, and the others go into the fortress. Iago stays behind to tell Roderigo that Desdemona is in love with Cassio and convince him to pick a fight with Cassio to cause mutiny and have him removed. Iago, in his second soliloquy, speaks again of his hatred for Othello. The details are not yet clear, but Iago plans to drive Othello mad.

2.2:
The herald reads a proclamation declaring a night of general festivities to celebrate both the destruction of the Turkish fleet and Othello’s recent marriage.

2.3:
Cassio, commanding the night watch during the time of feasting and drinking, takes his orders from Othello, who directs the soldiers to drink with moderation and keep the peace. Cassio and Iago, his second in command, will see to this. Then Othello and Desdemona retire to bed, the first night they will spend together since their marriage.

Alone, Iago makes suggestive remarks about Desdemona to Cassio, which Cassio turns aside; then Iago invites him to drink. Cassio declines, but Iago wheedles and urges him, until Cassio finally relents. Iago spurs Roderigo into a fight with Cassio; others join in and Iago sends Roderigo to ring the alarm bell, waking Othello and bringing him and his armed men to the spot. Othello demands to know who started the fight, and feigning reluctance, Iago names Cassio. Othello relieves Cassio of his post on the spot. Then he and Desdemona return to bed.

Iago advises Cassio to ask Desdemona to speak on his behalf with her husband. Cassio agrees, and Iago uses his wife, Emilia, to arrange a private meeting between Cassio and Desdemona.

Act Three. Scene One:
Cassio meets with a group of musicians and a clown (a countryman) whom he sends to find Emilia. Iago sends Emilia out to speak with him, and she reports that Desdemona and Othello are discussing the events of last night. Desdemona has spoken up for Cassio, and Othello, who likes him, has undertaken to bring him back into favor when the right moment comes.

3.2:
Othello sends a letter back to Venice by ship and makes an inspection of the fortifications.

3.3:
Cassio speaks to Desdemona, asking her to intercede with Othello on his behalf. Desdemona willingly agrees, knowing that Cassio is an old friend of Othello’s. She promises to speak of him with her husband repeatedly until the quarrel is patched up and Cassio is recalled.

When Othello and Iago enter, Cassio, who is embarrassed because of his antics the previous night, embraces Desdemona and departs. Iago seizes the opportunity to make an undermining comment—“Ha, I like not that”—that rankles in Othello’s mind. Desdemona speaks of Cassio, and Othello, to please her, agrees to see him, but he is distracted by his private thoughts.

In a conversation with Iago, in which Iago continues to imply that he knows something that he refuses to divulge, Othello denies that he would give himself over to jealousy. In his denial, he shows himself most vulnerable. He is consumed with doubt and suspicion. Othello voices his old fears that Brabantio was right, that it was unnatural for Desdemona to love him, that he was too horrible to be loved, and that it could not last. Iago leaves, and Othello contemplates his situation: He could be tricked, married to a woman who is already looking at other men, and he fears that he must wipe her out of his heart. He tries to tell himself that it is not true.

When Desdemona re-enters, Othello’s aspect is changed; he watches her intently, looking for signs, and brushes away her handkerchief when she seeks to sooth him. They go in to dinner, and Emilia picks up the fallen handkerchief, one that her husband, Iago, often urged her to steal from Desdemona. Emilia decides to have a copy made to give to Iago, but he enters, sees the handkerchief, and snatches it from her.

When Othello enters, Iago sees that Othello cannot regain his peace of mind. His speech is fevered, sweeping and frantic; he believes that his wife has been unfaithful to him. Othello then turns on Iago with savage intensity and demands to see the proof of Desdemona’s infidelity. Cornered, Iago produces the dream story: Cassio spoke in his sleep, embraced him, called him Desdemona, and cursed the Moor. Iago tells Othello that he has seen Cassio wipe his brow with a handkerchief embroidered with strawberries; Othello recognizes this handkerchief as the one he gave to Desdemona.

Othello dismisses love and calls for vengeance. Certainty has freed his mind from doubt and confusion. Now he swears action, and Iago swears to help him. Othello wants Cassio dead, Iago agrees to do it, and then Othello wonders how to kill Desdemona.

3.4:
Desdemona sends for Cassio to tell him that she has spoken with Othello; she is also worried that she has lost her handkerchief. When Othello enters, he claims a headache and asks her for a handkerchief to bind his head, but he will have only the embroidered strawberry handkerchief. In vain, Desdemona tries to deflect his questions about the handkerchief, speaking again of Cassio. Othello walks out in fury.

Cassio gives Bianca Desdemona’s handkerchief, which he found in his lodgings (Iago had placed it there) and asks her to make a copy of it for him, as he will have to return the original when he finds the owner. Bianca immediately recognizes it as belonging to a woman and berates Cassio for having another mistress.

Act Four. Scene One:
In a conversation with Othello, Iago says that Cassio has confessed to sex with Desdemona. This revelation is too much for Othello, who becomes incoherent and faints. When Cassio enters, Iago claims that Othello has epilepsy and has had seizures before. Rather than revive him, they must let the fit take its course. Iago sends Cassio away, telling him to come back later. Othello, regaining consciousness, talks of himself as one among many cuckolds, but Iago tells him to hide and observe Cassio, who is returning. Iago says he will draw Cassio out to tell of his amorous adventures with Desdemona.

Othello withdraws, too emotionally involved to understand that Iago is manipulating him, and Iago talks with Cassio about Bianca. Othello sees his smiles and laughter but cannot hear the details and believes he is joking about how much Desdemona loves him. Then Bianca herself enters, with Desdemona’s handkerchief, which she throws back at Cassio. Seeing his wife’s handkerchief in the hands of Cassio’s mistress is, for Othello, the “ocular proof” he sought. He is now convinced of Desdemona’s infidelity and knows he must kill both Cassio and Desdemona that very night.

4.2:
Othello questions Emilia about Desdemona, but she assures him that nothing immodest has taken place between her mistress and Cassio. Othello, rather than abandon his suspicions, believes Desdemona is so cunning that she has managed to deceive even her maid. Othello speaks with Desdemona in private, threatening to banish her and calling her “whore” and “strumpet”—charges that she immediately denies.

Emilia comes in, and Othello leaves. Exhausted, Desdemona knows that she is being punished, but she does not know what for. Emilia suspects that some villain has turned Othello against his wife and stirred up his jealousy. When Desdemona asks Iago’s advice, he says that it is only the business of the state that makes Othello angry.

Later, in a conversation with Iago, Roderigo confesses that he has had enough of his romantic quest and plans to withdraw. Iago makes a bold move, linking his two plots together: He urges Roderigo to kill Cassio, explaining that Cassio’s death will prevent Othello being sent elsewhere and, therefore, keep Desdemona in Cyprus. Roderigo allows himself to be persuaded.

4.3:
After the supper, Othello orders Desdemona to go to bed and to dismiss her attendant. Desdemona and Emilia discuss the situation; Emilia sees the marriage with Othello as a mistake, but Desdemona regrets nothing. She has a premonition of death and requests Emilia, if she should die, to wrap her body in one of her wedding sheets, which are now on the bed. Desdemona sings the “Willow Song,” remembering the maid Barbary whose lover went mad and abandoned her, and she died singing this song.

Act Five. Scene One:
In the street at night, Iago directs Roderigo to ambush Cassio. When Cassio approaches, Roderigo attacks unsuccessfully and is wounded by Cassio. Iago, from behind, stabs Cassio in the leg and runs away while Cassio cries murder. Othello, hearing Cassio’s cry, believes that Iago has done the job he has undertaken. Following Iago’s lead, Othello must harden his heart against the charms of his wife and spill her blood in the bed where she has betrayed him.

5.2:
Desdemona lies asleep in bed, and Othello enters, dreadfully calm and sure in what he must do. Desdemona wakens and calls him to bed, but he tells her to pray at once, repenting anything she needs to repent, and he will wait while she prays because he does not want to kill her soul. Suddenly, Desdemona realizes that Othello intends to kill her. She is afraid, although she knows she is not guilty. Knowing that she cannot convince him of her fidelity, Desdemona weeps and begs him to banish her rather than kill her, or let her live just a little more, but he stifles her, presumably with a pillow.

When Emilia knocks on the door, Othello draws the bed-curtain across, hiding the bed, and opens the door to hear the news. What Emilia reports is not what Othello expected. She says that Cassio has killed Roderigo. Then Desdemona’s voice is heard from the bed, saying “falsely murdered” and Emilia calls for help. Desdemona says that she is innocent, denies that anyone has killed her, and dies.

Emilia and Othello confront each other. Emilia sees herself as a witness and will tell what she has seen, and Othello declares that he has killed Desdemona because of her infidelity. Emilia insists that Desdemona was faithful; Othello replies that Cassio had been with her, and Iago knew all about it. Now Emilia has the key idea. She says “my husband” over and over, while Othello pours out his heart on justice and how he loved her and how Iago is honest. Emilia curses Iago, calls him a liar, and cries murder to waken everyone.

Montano, Gratiano, Iago, and others rush into the bedchamber where Emilia is shouting, and she challenges Iago to defend himself, giving him one last chance to retrieve himself in her estimation. Iago says that Desdemona was indeed unfaithful with Cassio, but Emilia knows this is untrue. She tells how she found the handkerchief, which her husband had asked her to steal, and gave it to him. Iago stabs Emilia and runs out. As she dies, Emilia tells Othello that Desdemona loved him. Othello realizes, too late, that he had been tricked and manipulated.

Iago is caught and brought back. Othello and Cassio demand to know why he did it, but Iago refuses to explain and says he will never speak again. Othello, watching his world unravel, asks the men to remember him clearly, his good points and his bad, as “one that lov’d not wisely, but too well.” Then he stabs himself, falls onto the bed, and dies.

Lodovico takes charge, giving Othello’s house and property to Gratiano, his next of kin by marriage. Cassio will be commander and have the power to sentence Iago, and Lodovico will return to Venice with the sad news.