Lady Macbeth requests that the, "sprits that tend on mortal thoughts," to unsex her, and fill her with the "direst cruelty…" She approaches Macbeth with her intent to kill King Duncan. Macbeth, although wanting the prophecy to come true, and become king, lacks the enthusiasm of his wife, to commit the murder of Duncan. Lady Macbeth urges Macbeth to act on his desires or he will think of himself as a coward. Maybe the dishonour that being a coward would bring is too great a burden for “brave Macbeth”.
King Duncan is invited to Macbeth’s castle, and it is there that he will be killed. Lady Macbeth encourages Macbeth to "look like the innocent flower, but be the serpent under it." Lady Macbeth wants Macbeth to act as he normally would, to appear to be happy with the King’s visit and keep his evil plan inside his head where it eats away at Macbeth’s sanity. Macbeth shows signs of insanity, as he follows a dagger up the stairs to Duncan’s bedroom, "is this a dagger which I see before me, let me clutch thee." Macbeth tells Lady Macbeth “I have done the deed” it seems that not only is he struggling with his morality but also his sanity this could also be a factor in the downward spiral of Macbeth.
After Duncan’s death has been discovered Macbeth is questioned. During the questioning Macbeth nearly gives himself away under the pressure so Lady Macbeth faints to cause a distraction.
The witches´ prophecy concerning Banquo´s descendants and Macbeth’s feeling of inferiority to Banquo lead Macbeth to arrange for the murder of Banquo and his son Fleance. The thought that it will be Banquo´s son who takes over the thrown from Macbeth rather than his own child makes him very angry. Macbeth believes that "none but he…I do fear."
There is a great contrast before and after the he meets the witches. Their prophecy has changed him from being a hero to the traitor he is now. In a way they pass on their evil into him.
The other encounter of the supernatural is the appearance of the dagger. This object seems to be confirming the fate the witches have given Macbeth. As it restarts his urge for power and also I believe it is an urge to appease his wife and her own appetite for power. However I will talk about this in more detail later on. The influence of his wife is greatly over exaggerated in my opinion. She may have given moral support and encouragement to Macbeth but if he really wanted to be king then he would have done the deed anyway. However I don’t think Macbeth ever wanted to kill Duncan, it was Lady Macbeth that wanted to do the deed but couldn’t as he resembled her father. The letter is the turning point for lady Macbeth just as the meeting with the weird sisters is Macbeth's. From that point on she is drastically transformed.
The banquet scene is where Macbeth is at his lowest, here he has a breakdown and Lady Macbeth challenges his manhood. After this Macbeth decides to see the witches to give him more advice. They tell him that no one of woman born will be able to harm him. This news lifts Macbeths morale.
Near the end of the play where Macbeth finds that Lady Macbeth has died, he does not seem very bothered “She should have died hereafter”. Instead he is a lot more concerned about loosing the crown.