Act III, Scene III of William Shakespeare's "Othello" is an important scene that underscores Iago's deceitful plan to destroy Cassio. Iago takes advantage of every relationship, including his own wife, Emilia, to undermine Cassio. .

             As the scene opens, Cassio has come to Desdemona to ask her to plead his cause to Othello, hoping to regain his rank and Othello's loyalty. She assures him that she will speak with her husband on his behalf, to which Cassio replies that he has never been anything but her true servant. When Othello questions whether it was Cassio who had just left his wife, Iago seizes the opportunity to begin planting seeds of doubt concerning Cassio's intentions toward Desdemona, saying that surely Cassio would not "steal away so guilty-like, seeing you coming" (Shakespeare). He then cautions Othello to beware that jealousy does not consume him, but adds, "Look to your wife; observe her well with Cassio" (Shakespeare).

             Othello shuns all affections from Desdemona, and even refuses her gesture of tending his headache with her handkerchief, one that was his first gift to her, and drops it on the floor. Emilia knew that her husband wanted this handkerchief and so she picks it up and gives it to Iago, who in turn places it in Cassio's room. Iago further flames the fire of jealousy by telling Othello that he heard Cassio speaking in his sleep saying, "Sweet Desdemona, let us be wary, let us hide our loves," and then claimed that Cassio griped his hand and kissed him (Shakespeare). He further claimed that Cassio had the handkerchief, and that he had seen Cassio wipe his beard with it. .

             Othello responds to this by demanding, "Within these three days let me hear thee say that Cassio's not alive," to which Iago replies, "tis done at your request" (Shakespeare). Othello damns Desdemona, as Iago vows his eternal loyalty to Othello.