The Turkish fleet is destroyed in a storm, while Cassio and then Desdemona, Emilia, and Iago arrive safely at Cyprus. Desdemona anxiously waits for Othello. When his ship arrives, he and Desdemona joyfully greet each other. Iago, putting his plot into action, persuades Roderigo that Desdemona is in love with Cassio and that Roderigo should help get Cassio dismissed from the lieutenancy.

Iago gets Cassio drunk, making it easy for Roderigo to provoke Cassio into a brawl, first with Roderigo, then with Montano, whom he wounds. Othello, called from his bed by the noise, stops the brawl and strips Cassio of his lieutenancy. Iago advises Cassio to seek Desdemona’s help in getting reinstated. The next step in Iago’s plan is to tell Othello that Desdemona supports Cassio because Cassio is her lover.