Banquo suspects Macbeth but gains comfort from the second part of the Witches' prediction — that his own children will be kings. Having announced his intention to go riding with Fleance, Banquo is persuaded by the Macbeths to return later that evening to their new palace at Forres for a special feast. However, Macbeth realizes that the Witches' prophecy regarding Banquo represents a threat to his own position. Unable to endure the thought of Banquo's descendants claiming his position, Macbeth summons two hired murderers and confirms with them prior arrangements for the killing of Banquo and Fleance.
Act Three, Scene Two
This short scene allows the audience once more into the private thoughts of the murderous couple, while holding the action momentarily in suspense. As the hired killers make their way toward Banquo, Macbeth and his wife meet secretly. His wife attempts to soothe his troubled mind but ironically feels the same doubts herself. Killing the king has provided them with many more difficulties than they first envisioned. To the astonishment of his wife, Macbeth reveals his plan to murder Banquo.
Act Three, Scene Three
The hired murderers meet as arranged. On hearing approaching horses, a signal is given, and Banquo and his son Fleance are attacked. The murderers' lantern is accidentally extinguished, and the job is left half-done: Although Banquo is killed, Fleance escapes.
Act Three, Scene Four
At Forres, Macbeth and his wife welcome the thanes of Scotland to the banquet. Immediately prior to the feast, one of the murderers appears at a side door and reveals to Macbeth the truth about the mission: their success in the killing of Banquo and their failure to murder Fleance. Macbeth recomposes himself and returns to the table. As he raises a toast to his absent friend, he imagines he sees the ghost of Banquo. As with the ethereal dagger, the ghost of Banquo appears to come and go, propelling Macbeth into alternating fits of courage and despair. Lady Macbeth invites the thanes to depart and, once alone, tries one last time to soothe her husband. But Macbeth's paranoid mind is already on to the next murder, that of Macduff. To ascertain his future with greater certainty, he makes clear his intention to visit the Weird Sisters once more.
Act Three, Scene Five
Hecate, the classical goddess of the lower world who represents the spirit of ancient witchcraft, calls the weird sisters to her to complain that her own part in Macbeth's downfall has been overlooked and that she now wishes personally to make his downfall complete. The scene is unnecessary to understanding the play and was probably not written by Shakespeare.
Act Three, Scene Six
Meeting with a rebel lord, Lennox reveals his doubts concerning Macbeth. His argument is that those who might be immediately suspected of murdering their kinsmen are less likely to have done so than Macbeth, who had killed the guards of Duncan's chamber so hastily. Although Lennox is prepared to accept Macbeth's actions, he cannot help feeling deeply suspicious of him. The other lord reveals to Lennox that Macduff has fled from Scotland to join forces with Malcolm in England. Moreover, they have requested help from England's King Edward the Confessor. Both Lennox and the other lord pray that God's vengeance may swiftly fall on the tyrannical Macbeth and that Scotland may return to peace once more.