Iago has convinced Othello that Desdemona is unfaithful with Cassio. Othello plans to strangle her; Iago promises to kill Cassio. Venice has appointed Cassio to replace Othello. Iago urges Roderigo to ambush Cassio after supper, claiming his death will prevent Othello from taking Desdemona away.
Othello leaves with Lodovico, ordering Desdemona to bed and telling her to dismiss Emilia. As Emilia helps her undress, Desdemona sings a song remembered from her mother’s maid and asks to be shrouded in her wedding sheets if she dies first. They discuss wives’ infidelity: Desdemona rejects it, while Emilia says husbands’ conduct can lead wives to it.
Who attacks Cassio first?