Iago complains to Roderigo that he was not named Lieutenant by Othello, but rather Ensign. Othello, the Moorish general, made Cassio Lieutenant. Iago is enraged at his misfortunate and declares his hatred for the Moor. Roderigo, a Venetian gentleman is in love with Desdemona, the daughter of Senator Brabantio. Iago awakens Brabantio in the middle of the night to notify him of his daughter's elopement with Othello, much to everyone's surprise and disapproval. The Duke oversees the case between Brabantio and Othello, whom he believes to have bewitched his daughter with magic. Desdemona informs her father that she is in love with Othello and has married him.
Othello leaves for Cyprus and Desdemona soon follows him there. In Cyprus, Iago begins his devilish plan of destruction. During a festive evening celebrating the nuptials of Desdemona and Othello, Iago sends Roderigo to stir Cassio. A typically sober Cassio takes to the bottle at Iago's generosity, and then falls into duel with Roderigo. Because of the chaos, Cassio's reputation is seemingly smeared and his relationship becomes troubled with Othello. Iago tells Cassio to ask Desdemona to speak with Othello on his behalf. By doing so, Iago will plan the seed of jealousy in Othello's mind that Cassio and Desdemona are having an affair. Cassio befriends Desdemona, who does, in fact, attempt to sway Othello in his behalf. As she speaks with her beloved husband, however, Iago infers that her words are not platonic, but amorous. Othello slowly transforms into a jealous monster. Despite this meaningless talk, Othello demands proof and evidence of such an affair.
During one of their conversations, Desdemona drops her treasured handkerchief on the floor. Emilia picks it up and gives it to Iago at his request. The handkerchief is an Egyptian heirloom that Othello gave to Desdemona as the first symbol of his love for her. Iago plants it in Cassio's room so that he may show Othello proof of his relationship with Desdemona. Upon realization of such a fact, Othello becomes mad with rage. Bianca, the common seamstress mistress of Cassio, also becomes jealous when she sees the handkerchief in Cassio's room, for she also believes him to be having an affair.
Iago and Roderigo continue to pursue Iago's destruction of Othello. Roderigo, however, is in the way of Iago's evil, so Iago kills him in the dark and blames others for Roderigo's death. Othello is torn between his love for his wife and his jealousy and hatred of such a possible 'whore,' so he smothers Desdemona to death. Emilia enters and witnesses her dying mistress. She tells Othello that he is misled and that Desdemona was never unfaithful. Iago enters and tries to persist with his plan, yet his wife disrupts his action. As Emilia tells Othello the truth behind Iago's trickery, Iago stabs and kills her. Montano, Lodovico, Gratiano, and Cassio enter the bedroom to bring news. They have found letters in Roderigo's pocket explaining Iago's entire scheme. Othello stabs Iago, leaving him to live in pain, and then, before banishment, from Cyprus, kills himself.
