When they have heard the Banquo had died, Macbeth was angered because the murderers were not able to kill Fleance. The King saw the ghost of Banquo sitting on his throne. Macbeth was very surprised and tried to talk to the ghost which he was the only person who could see. Lady Macbeth tried to save her husband's face by saying telling the ghost to disregard Macbeth's behavior. She scolded him and told him to act normally.
This scene is terrifying in a more psychologically disturbing way—the room looks fresh, as if Rebecca herself is still there living in it.