In the royal palace at Forres, Banquo paces and thinks about the coronation of Macbeth and the prophecies of the weird sisters. The witches foretold that Macbeth would be king and that Banquo’s line would eventually sit on the throne. If the first prophecy came true, Banquo thinks, feeling the stirring of ambition, why not the second? Macbeth enters, attired as king. He is followed by Lady Macbeth, now his queen, and the court. Macbeth and Lady Macbeth ask Banquo to attend the feast they will host that night. Banquo accepts their invitation and says that he plans to go for a ride on his horse for the afternoon. Macbeth mentions that they should discuss the problem of Malcolm and Donalbain. The brothers have fled from Scotland and may be plotting against his crown.

Banquo departs, and Macbeth dismisses his court. He is left alone in the hall with a single servant, to whom he speaks about some men who have come to see him. Macbeth asks if the men are still waiting and orders that they be fetched. Once the servant has gone, Macbeth begins a soliloquy. He muses on the subject of Banquo, reflecting that his old friend is the only man in Scotland whom he fears. He notes that if the witches’ prophecy is true, his will be a “fruitless crown,” by which he means that he will not have an heir (III.i.62). The murder of Duncan, which weighs so heavily on his conscience, may have simply cleared the way for Banquo’s sons to overthrow Macbeth’s own family.

The servant reenters with Macbeth’s two visitors. Macbeth reminds the two men, who are murderers he has hired, of a conversation he had with the two men the day before, in which he chronicled the wrongs Banquo had done them in the past. He asks if they are angry and manly enough to take revenge on Banquo. They reply that they are, and Macbeth accepts their promise that they will murder his former friend. Macbeth reminds the murderers that Fleance must be killed along with his father and tells them to wait within the castle for his command.

Elsewhere in the castle, Lady Macbeth expresses despair and sends a servant to fetch her husband. Macbeth enters and tells his wife that he too is discontented, saying that his mind is “full of -scorpions” (III.ii.37). He feels that the business that they began by killing Duncan is not yet complete because there are still threats to the throne that must be eliminated. Macbeth tells his wife that he has planned “a deed of dreadful note” for Banquo and Fleance and urges her to be jovial and kind to Banquo during the evening’s feast, in order to lure their next victim into a false sense of security (III.ii.45).

It is dusk, and the two murderers, now joined by a third, linger in a wooded park outside the palace. Banquo and Fleance approach on their horses and dismount. They light a torch, and the murderers set upon them. The murderers kill Banquo, who dies urging his son to flee and to avenge his death. One of the murderers extinguishes the torch, and in the darkness Fleance escapes. The murderers leave with Banquo’s body to find Macbeth and tell him what has happened.

After his first confrontation with the witches, Macbeth worried that he would have to commit a murder to gain the Scottish crown. He seems to have gotten used to the idea, as by this point the body count has risen to alarming levels. Now that the first part of the witches’ prophecy has come true, Macbeth feels that he must kill his friend Banquo and the young Fleance in order to prevent the second part from becoming realized. But, as Fleance’s survival suggests, there can be no escape from the witches’ prophecies.

Macbeth and his wife seem to have traded roles. As he talks to the murderers, Macbeth adopts the same rhetoric that Lady Macbeth used to convince him to murder in Act I, scene vii. He questions their manhood in order to make them angry, and their desire to murder Banquo and Fleance grows out of their desire to prove themselves to be men. In the scene with Lady Macbeth that follows, Macbeth again echoes her previous comments. She told him earlier that he must “look like the innocent flower, / But be the serpent under’t” (I.v.63–64). Now he is the one reminding her to mask her unease, as he says that they must “make [their] faces visors to [their] hearts, / Disguising what they are” (III.ii.35–36). Yet, despite his displays of fearlessness, Macbeth is undeniably beset with guilt and doubt, which he expresses in his reference to the “scorpions” in his mind and in his declaration that in killing Banquo they “have scorched the snake, not killed it” (III.ii.15).

While her husband grows bolder, Lady Macbeth begins to despair—“Naught’s had; all’s spent,” she says (III.ii.6). It is difficult to believe that the woman who now attempts to talk her husband out of committing more murders is the same Lady Macbeth who earlier spurred her husband on to slaughter. Just as he begins to echo her earlier statements, she references his. “What’s done is done” (III.ii.14), she says wishfully, echoing her husband’s use of “done” in Act I, scene vii, where he said: “If it were done when ’tis done, then ’twere well / It were done quickly” (I.vii.1–2). But as husband and wife begin to realize, nothing is “done” whatsoever; their sense of closure is an illusion.

Both characters seem shocked and dismayed that possessing the crown has not rid them of trouble or brought them happiness. The language that they use is fraught with imagery suggestive of suspicion, paranoia, and inner turmoil, like Macbeth’s evocative “full of scorpions is my mind, dear wife” (III.ii.37). Each murder Macbeth commits or commissions is intended to bring him security and contentment, but the deeper his arms sink in blood, the more violent and horrified he becomes.

By the start of Act III, the play’s main theme—the repercussions of acting on ambition without moral constraint—has been articulated and explored. The play now builds inexorably toward its end. Unlike Hamlet, in which the plot seems open to multiple possibilities up to the final scene, Macbeth’s action seems to develop inevitably. We know that there is nothing to stop Macbeth’s murder spree except his own death, and it is for that death that the audience now waits. Only with Macbeth’s demise, we realize, can any kind of moral order be restored to Scotland.