King Duncan has learnt about the defeat of Macdonwald from an injured sergeant. The Thane of Ross also informs him that the Thane of Cawdor is a traitor and his been captured. Scotland has won the war. Duncan is very happy with Macbeth and names him the new Thane of Cawdor.
Macbeth and Banquo are on their way back to Forres when they come across the three witches. The witches tell Macbeth that he will become the Thane of Cowder and the king after. They also tell Banquo that his children will be kings although he will not be one. The witches disappear.
Macbeth is debating committing murder when Lady Macbeth walks in and tries to convince him. She tells him he will be a coward in her eyes if he does not kill Duncan. Macbeth agrees to her plan.
English forces reach the castle and remove their camouflage. Macbeth kills young sidward. Macduff reveals he is not born of woman, kills Macbeth and claims Malcolm king of scotland.