Summary and Commentary on Act 3 (Scene iv-vi).
Scene IV comes just after the murder of Banquo. It is the most important scene where Macbeth is celebrating his kingship but he is not able to do so properly. Here in the banquet, Macbeth and Lady Macbeth is busy welcoming their guests. The mood of the play at this particular time is ebullient but soon the mood and the atmosphere changes when one of the murderers enters the scene to inform the success of killing Banquo and the escape of Fleance. The murderer is asked to leave. Then Macbeth announces out loud that the banquet would have been wonderful if Banquo would have been present. At that point, Banquo's Ghost appears and sits on Macbeth. Macbeth shocked to see Banquo tells his guests that the "table is full" when he was asked to take his seat. He then talks to the ghost ("Thou canst not say I did it. Never shake / Thy gory locks at me.") Which confuses the guests but Lady Macbeth tells them that it is just a "fit" that has been happening since his childhood. She then goes aside and convinces Macbeth that it's just his hallucination like the dragger he saw before he murdered Duncan. Momentarily the ghost disappears and Macbeth announces that he has "a strange infirmity" that they should overlook. .
When the party was starting again, Macbeth offers a toast in the name of Banquo. At once, the ghost reappears and Macbeth starts scolding it. Then the ghost vanishes again. Lady Macbeth gets furious once more and in order to stop any kind of suspicion he asks the guests to leave telling them that Macbeth is not well. As the guests leave, Macbeth plans to go meet the three witches to inquire more about his future.
Scene V is where the three witches meet Hecate (the queen of witches) who scolds them for not including her in Macbeth's affaires. She plans to prepare some portion for Macbeth and tells them to prepare for his downfall.
Scene VI is where there is discussion between Lennox and the Lord.