Cyprus, during a storm. Otello arrives victorious. His duet with Desdemona is among the most beautiful things ever written: two people deeply in love, recounting how they fell for each other. Meanwhile, Iago begins to weave his web.

Iago plants in Otello's mind the suspicion that Desdemona is betraying him with Cassio. He gives him no proof — only doubts, whispers, insinuations. Then he fabricates 'evidence': a handkerchief that ends up in Cassio's hands. For Otello, it is certainty. Jealousy transforms him: the noble man we knew disappears. He becomes cruel, humiliates Desdemona in public.

Desdemona prepares for the night. She sings the 'Willow Song', a melancholy melody she had learned as a child. She prays. Otello enters. He asks her to confess the betrayal. She denies it, begs him. He strangles her. Then Iago is unmasked. Otello understands everything. He looks at Desdemona's body, kisses her one last time, and stabs himself.