The scene begins with Banquo talking about the prophecy. He feels, that Macbeth "play’dst most foully for’t", but the predictions have come true, and now Banquo considers his own part of the prophecy - that his sons will be kings. Such a pity to see the true, valiant Banquo also coming to the "dark side".
Meanwhile, Macbeth (already a king) doesn't feel safe while Banquo, who knows the prophesy and suspects him, is around. So he hires two killers to get rid of Banquo and his son when they come back from their trip on the horseback. I guess, this doesn't mean he repents much of the murder, eh? Note, that Macbeth has taken initiative in evil, and later he doesn't even tell his wife what he has planned.
Lady Macbeth comes to her husband to give him some consolation and encourage him to "be bright and jovial among his guests to-night". But they both suffer from the consequences of their deed and they are both unsafe, as they think that Banquo and his son endanger their rule. "Full of scorpions is my mind" says Banquo, and he tells his wife that he has ordered to kill both the father and the son in some hope of tranquillity. But I doubt they will have any tranquillity now after such a deed. As one lie entails another, one murder entails more murders. That's how the world works.
A short scene, in which Banquo is killed in the ambush of the killers, but his son manages to escape, following his father's last words:
O, treachery! Fly, good Fleance, fly, fly, fly!Scene 4
Thou mayst revenge. O slave!
Blood hath been shed ere now, i’ the olden time,In the banquet scene the ghost of Banquo seems to represent conscience, as only Macbeth can see him, and as it appears when Macbeth speaks about Banquo's absence.
Ere human statute purged the gentle weal;
Ay, and since too, murders have been perform’d
Too terrible for the ear: the times have been,
That, when the brains were out, the man would die,
And there an end; but now they rise again,
With twenty mortal murders on their crowns,
And push us from our stools: this is more strange
Than such a murder is.
Macbeth's madness has completely betrayed him, but Lady Macbeth tries to conceal the truth, she tries to protect her husband by saying it's only a short fit and by asking everybody away. She doesn't even blame him for the scene after everybody have left. What a good and true wife, isn't she?
Macbeth understands now, that "blood will have blood", but he is not sure of his way, and he decides to seek the advice of the witches again:
I will to-morrow,
And betimes I will, to the weird sisters:
More shall they speak; for now I am bent to know,
By the worst means, the worst. For mine own good,
All causes shall give way: I am in blood
Stepp’d in so far that, should I wade no more,
Returning were as tedious as go o’er:
Strange things I have in head, that will to hand;
Which must be acted ere they may be scann’d.
Enters Hecate, all rage because she wasn't invited to take part in playing with Macbeth's fate. For those who den't remember, "Hecate or Hekate is an ancient goddess, frequently depicted in triple form and variously associated with crossroads, entrance-ways, fire, light, the Moon, magic, witchcraft, knowledge of herbs and poisonous plants, necromancy, and sorcery" (Wikipedia). Well, first the ghost, now this... It gets stranger and stranger.
Two noble lords ironically discuss the recent events:
My former speeches have but hit your thoughts,So nice, isn't it? "Men must not walk too late". Note that Macbeth is called a tyrant for the first time in this scene.
Which can interpret further: only, I say,
Things have been strangely borne. The gracious Duncan
Was pitied of Macbeth: marry, he was dead:
And the right-valiant Banquo walk’d too late;
Whom, you may say, if’t please you, Fleance kill’d,
For Fleance fled: men must not walk too late.
Who cannot want the thought how monstrous
It was for Malcolm and for Donalbain
To kill their gracious father? damned fact!
How it did grieve Macbeth! did he not straight
In pious rage the two delinquents tear,
That were the slaves of drink and thralls of sleep?
Was not that nobly done? Ay, and wisely too;
For ’twould have anger’d any heart alive
To hear the men deny’t. So that, I say,
He has borne all things well: and I do think
That had he Duncan’s sons under his key —
As, an’t please heaven, he shall not — they should find
What ’twere to kill a father; so should Fleance.
Meanwhile we get to know that Macduff has gone to the English court where Duncan's son resides and enjoys the favour of the English king to ask for the restoration of order in Scotland. And the lords wait for the news with hope.