Towards the end of the story, the clock in the black room alerts Prospero and his guests that it is midnight. While the ringing of the clock unsettles people at every hour, the midnight bells are uniquely jarring because they ring for a lengthy twelve notes. Through the disorienting haze immediately after the twelve bells, Prospero and the other members of the nobility notice a new partygoer moving slowly and solemnly through the waltzers. The mysterious new guest astounds the revelers because it should have been impossible for anybody to enter the estate given that the inhabitants welded the gates shut. The mysterious guest is also dressed for a masquerade ball but his presence is more ghoulish and more sinister than that of the rest of the partygoers, and generates feelings of “terror,” “horror,” and “disgust.” In addition to his impossible arrival, the mysterious guest’s apparel causes great alarm. The guest is swathed in garments that resemble a funeral shroud. To make matters worse, the figure’s mask looks like the face of a recently deceased corpse. The corpse-like face is so realistic that it would still look real even under close scrutiny. The mysterious guest’s mask is the most unsettling aspect of his appearance because the face is adorned with spots of scarlet blood, suggesting he is a victim of the Red Death. 

At first, Prospero is frightened by the mysterious guest. However, his fear quickly gives way to fury because he interprets the mysterious guest’s appearance as an insult. Prospero becomes enraged that someone with so little humor and levity would join his party and mock his efforts to remain untouched by the deadly disease. Prospero calls on his knights and dames to seize the interloper so that the mysterious guest can be unmasked and subsequently executed for his transgressions. However, the courtiers are so afraid of the figure that they refuse to touch him or even go near him. Unchecked, the mysterious guest proceeds to walk through each room beginning in the blue room. Prospero raises his dagger and charges forward through the colored rooms alone after realizing that nobody in his court has any intention of detaining the trespasser. Prospero finally catches up to him in the black room and drops dead the moment he is in the presence of the mysterious guest. When other party-goers enter the room to attack the cloaked figure for killing their prince, they find that there is nobody beneath the costume. All 1,000 of the estate’s inhabitants immediately die upon finding the disembodied cloak, for the Red Death has infiltrated the castle. “Darkness and Decay and the Red Death” have at last triumphed.