The Witches meet upon the Heath and plan to meet Macbeth and Banqou !
They predict that Macbeth will be made Thane of Cawdor and eventually become King of Scotland. They also tell Banquo that although he will never be king, his descendants will; the Witches then vanish.
Duncan is due to stay with the Macbeths as a house guest. When Lady Macbeth receives Macbeth's news in a letter, she resolves to make the most of the situation. Macbeth and his wife plan and carry out Duncan's murder.
Lady Macbeth drugs the guards wine so that Macbeth can enter and kill Duncan. After, Macbeth regrets it but is reassured by Lady Macbeth. They leave the dagger by the kings side.
When Macduff discovers the murder, Macbeth kills the drunken guards in a show of rage and retribution.
Duncan's sons, Malcolm and Donalbain, flee, fearing for their own lives; but they are, nevertheless, blamed for the murder.