The banquet scene in Act 3 is compelling drama because it uses dramatic irony and suspense.
After Macbeth kills Duncan, he starts to lose it. After Lady Macbeth gave him a plan and he followed it, Macbeth was firmly implanted as king. However, he does not feel comfortable there long. In order to act kingly, he has a banquet and invites some of his nobles. It does not go as planned.
Macbeth has hired murderers to kill Banquo, because he is worried that Banquo is a threat to him. Banquo was there when the witches made the prophecies, and there was even one concerning his son’s being king. So Banquo has to go.
When Macbeth comes to sit at the table after talking to the murderers, he gets a surprise.
The table's full.(55)
Here is a place reserved, sir.
Where? (Act 3, Scene IV, p. 50)
Macbeth does not see a place to sit, he sees a ghost in his empty chair. None of his guests see this. They are not sure what is wrong with him. However, this is an example of dramatic irony because the audience knows exactly what is going on. Macbeth has killed his friend, and he is now regretting it.
The suspense continues when Macbeth actually addresses the ghost, in front of all the people—to Lady Macbeth’s chagrin.
The time has been,
That, when the brains were out, the man would die,(95)
And there an end; but now they rise again, (p. 50)
Ross tries to end the party by suggesting Macbeth is not well, and Lady Macbeth makes a variety of lame excuses for him. (my lord is often thus,/And hath been from his youth” (p. 51). Eventually, the banquet has to be ended because Macbeth cannot be comforted.
The banquet scene is a real turning point in Macbeth. The audience and reader begins to notice that Macbeth is not terribly sane. Signs of guilt begin to creep in, both for Lady Macbeth and Macbeth. It is the beginning of the end for Macbeth’s reign—and the Macbeths.