ACT I In Venice, Roderigo is upset when he finds out that Desdemona is expected to marry Othello. He accuses Iago of fraud for making him--Roderigo--believe that Iago’s hatred of Othello would stand in the way of Othello’s love for Desdemona and pave the way to Desdemona's heart. They tell her father Brabantio about her secret love affair.
ACT II Several weeks pass,the storms have rendered the Turkish Fleet. Iago arrives in Cyprus. Cassio chats with Desdemona to keep her from worrying about her new husband. Iago sees this, then decides he should make a rumor about an affair between them. Roderigo starts a fight with Cassio under Iago's direction. Governor Montano intervenes and gets injured.
ACT III Desdemona assures Cassio that she will plead on his behalf. Iago convinces Othello to question Desdemona. Iago tells Othello that he heard Cassio talking in his sleep about making love to Desdemona. Infuriated, Othello makes Iago his new lieutenant.
ACT IV Iago is playing mind games with Othello as usual, forcing him to imagine Desdemona and Cassio in bed together. Othello is furious.Iago tells Othello to hide a little ways away so that he can overhear a conversation between Iago and Cassio. Where Cassio will clearly incriminate himself.Othello is completely convinced by this little scene. Othello threatens to kill Cassio and Desdomona.