Act I

Macbeth, Banquo and the Witches on the Heath Oil on canvas, 66 x53 inches From Macbeth Paintings

scene i
Thunder and lightning in  a Scottish moor. Three witches appear and make plan to meet Macbeth after battle.

 scene ii
At a military camp, Duncan, King of Scotland, asks a wounded captain for news about the  battle. The captain replies that the Scottish generals Macbeth and Banquo were fighting courageously on the battlefield.  As the captain is carried off to have his wounds attended to, the thane of Ross, a Scottish nobleman, enters and tells the king that the traitorous thane of Cawdor has been defeated and the army of Norway repelled. Duncan decrees that the thane of Cawdor be put to death and gives Cawdor's title to Macbeth. Ross leaves to deliver the news to Macbeth.

 scene iii
On the heath near the battlefield, thunder rolls and the three witches appear to meet Macbeth and Banquo. Macbeth and Banquo, on their way to the king's court at Forres, come upon the witches and shrink in horror at the sight of the old women. Banquo wonders whether they are really women, since they seem to have beards like men. The witches hail Macbeth as thane of Glamis and as thane of Cawdor. Macbeth is baffled by this second title, as he has not yet heard of King Duncan's decision. The witches also declare that Macbeth will be king one day. Stunned and intrigued, Macbeth presses the witches for more information, but they have turned their attention to Banquo, speaking in yet more riddles. They call Banquo "lesser than Macbeth, and greater," and "not so happy, yet much happier"; then they tell him that he will never be king but that his children will sit upon the throne (I.iii.63–64). Macbeth implores the witches to explain what they meant by calling him thane of Cawdor, but they vanish into thin air.

Macbeth and Banquo discuss the strange encounter. Their conversation is interrupted by the arrival of Ross and Angus, who have come to convey them to the king. Ross tells Macbeth that the king has made him thane of Cawdor, who has been executed for treason. Macbeth, amazed that the witches' prophecy has come true, asks Banquo if he hopes his children will be kings. Banquo replies that devils often tell half-truths in order to "win us to our harm" (I.iii.121). Macbeth ignores his companions and speaks to himself, ruminating upon the possibility that he might one day be king. He wonders whether the reign will simply fall to him or whether he will have to perform a dark deed in order to gain the crown. At last he shakes himself from his reverie and the group departs for Forres. scene iv
At the king's palace, Duncan hears reports of Cawdor's execution from his son Malcolm. Macbeth and Banquo enter with Ross and Angus. Duncan thanks the two generals profusely for their heroism in the battle, and they profess their loyalty and gratitude toward Duncan. Duncan announces his intention to name Malcolm the heir to his throne. Macbeth declares his joy but notes to himself that Malcolm now stands between him and the crown. Plans are made for Duncan to dine at Macbeth's castle that evening, and Macbeth goes on ahead of the royal party to inform his wife of the king's impending arrival. scene v
In Macbeth's castle, Lady Macbeth reads  a letter she has received from Macbeth. The letter announces Macbeth's promotion to the thaneship of Cawdor and details his meeting with the witches. Lady Macbeth murmurs that she knows Macbeth is ambitious, but fears he is too full of kindness to take the steps necessary to make himself king. She resolves to convince her husband to do whatever is required to seize the crown. A messenger enters and informs Lady Macbeth that the king rides toward the castle, and that Macbeth is on his way as well.  Lady Macbeth resolves to put her natural femininity aside so that she can do the bloody deeds necessary to seize the crown. Macbeth enters, and he and his wife discuss the king's forthcoming visit. Macbeth tells his wife that Duncan plans to depart the next day, but Lady Macbeth declares that the king will never see tomorrow. She tells her husband to have patience and to leave the plan to her.

scene vi
Duncan, the Scottish lords, and their attendants arrive outside Macbeth's castle. Duncan praises the castle's pleasant environment, and he thanks Lady Macbeth, who has emerged to greet him, for her hospitality. She replies that it is her duty to be hospitable since she and her husband owe so much to their king. Duncan then asks to be taken inside to Macbeth, whom he professes to love dearly.scene vii
Inside the castle, Macbeth is  pondering his idea of assassinating Duncan. He says that the deed would be easy if he could be certain that it would not set in motion a series of terrible consequences. He declares his willingness to risk eternal damnation but realizes that even on earth, bloody actions "return / To plague th'inventor" (I.vii.9–10). He then considers the reasons why he ought not to kill Duncan: Macbeth is Duncan's kinsman, subject, and host; moreover, the king is universally admired as a virtuous ruler. Macbeth notes that these circumstances offer him nothing that he can use to motivate himself. He faces the fact that there is no reason to kill the king other than his own ambition, which he realizes is an unreliable guide.

Lady Macbeth enters and tells her husband that the king has dined and that he has been asking for Macbeth. Macbeth declares that he no longer intends to kill Duncan. Lady Macbeth, outraged, calls him a coward and questions his manhood. He asks her what will happen if they fail; she promises that as long as they are bold, they will be successful. Then she tells him her plan: while Duncan sleeps, she will give his chamberlains wine to make them drunk, and then she and Macbeth can slip in and murder Duncan. They will smear the blood of Duncan on the sleeping chamberlains to cast the guilt upon them. Astonished at the brilliance and daring of her plan, Macbeth tells his wife that her "undaunted mettle" makes him hope that she will only give birth to male children (I.vii.73). He then agrees to proceed with the murder.