In Poe's short story "The Masque of the Red Death," why does Prince Prospero lock himself and his guests inside his castle?
During the short story, a deadly plague known as the Red Death sweeps through the countryside, killing thousands each day and depopulating Prince Prospero's dominions. This fatal, painful pestilence kills victims in half an hour and stains their bodies with blood before they die. However, Prince Prospero believes that he can outwit and escape Death by locking himself inside his lofty abbey along with his friends. While the population suffers outside the abbey walls, Prince Prospero holds a magnificent ball inside his estate around the fifth or sixth month of the plague. Prince Prospero feels that the high walls and strong iron gates of his abbey will be enough to defeat the Red Death, but he tragically finds out that he cannot escape Death. By the end of the story, an enigmatic being, essentially Death personified, enters Prospero's abbey and kills everyone attending the ball. One of Poe's themes throughout this short story is that individuals cannot escape certain death.
In Edgar Allan Poe's allegorical story "The Masque of the Red Death," the "Red Death" has swept through the country, devastating the population with a hideous and fatal pestilence. The epidemic causes "sharp pains, and sudden dizziness, and then profuse bleeding at the pores, with dissolution" all within the span of half an hour.
After half of the population is wiped out by this disease, Prince Prospero makes the selfish decision to sequester his personal friends (mostly knights, ladies, and other courtiers) within the castle in order to protect them from the Red Death. Beyond the iron gates of this stronghold, the commoners continue to suffer and die. This arrangement goes on for five or six months until Prospero decides to throw a masquerade and the embodiment of the Red Death arrives, spreading the disease to those who believed their wealth and social status could protect them.
The prince thought that if he isolated himself from the plague running rampart throughout the countryside, he would be able to avoid contamination. He invited a select few to be part of his court to keep him company. Also, in that way he could "play king" and pretend that everything was normal. However, the "out of sight, out of mind" principle did not work, as Death came to his very door.
Check out the reference below for further insight into the multiple meanings of the mask in this regard.