King Duncan meets up with Macbeth, Banquo, Ross and Angus. The men pledge loyalty to the king, and Duncan announces that his son, Malcolm, will succeed him as king and become a prince.
"Our eldest, Malcolm, whom we name hereafter the prince of Cumberland; which honor must not accompanied invest him only, but signs of nobleness, like stars, shall shine on all deservers."
Lady Macbeth reads the letter sent to her about Macbeth's meeting with the witches and fears that Macbeth lacks the ruthlessness to kill Duncan
"Yet I do fear thy nature; It is too full o' th' milk of human kindness."
Macbeth tries to argue why killing Duncan is a bad idea, but his wife mocks him and plans for Duncans murder.
"If we should fail-"
"We fail? But screw your courage to the sticking place and we'll not fail. When Duncan is asleep, his two chamberlains will I with wine and wassail so convince that memory, the warder of the brain, shall be a fume, and the receipt of reason a limbeck only."