The life of the people outside were suffering a great epidemic of the Red Death. According to Poe, this was a terrible disease whose symptoms included" sharp pains, and sudden dizziness, and then profuse bleeding at the pores . . ." The person looked so "hideous" that others shrank from being near one stricken with the disease. Within half an hour of showing symptoms, a person was dead. Over half of the kingdom had already died when Prospero invited his friends into his castle.
Inside the castle, people were having a great party. The prince had provided "all the appliances of pleasure." The party-goers decided that they simply wouldn't think about all the misery outside of the castle. Prospero simply boarded up his "castellated abbey" and no one could enter or leave. "The external world could take care of itself. In the meantime it was folly to grieve, or to think." The inhabitants of the castle felt safe because they thought they had escaped death and therefore could have a grand time while misery reigned in the countryside. That is, until the sixth month when Prospero decided to throw a masquerade party.
In "The Mask of the Red Death," the major difference among the guests of Prospero (his name suggests it) and those left outside the palace is wealth and social position. Those who do not possess these traits in Prospero's "dominion" are subjected to the "Red Death," suffering "sharp pains, and sudden dizziness, and then profuse bleeding at the pores...and seizures." Within thirty minutes they are dead.
Prince Prospero, who "was happy and dauntless and sagacious," feels that he can fortify himself and those of his realm against the plague of the "Red Death." He invites "knights and dames of his court" to his palace for a masked ball and does include "buffoons," ballet dancers, musicians, and servants. His oddly decorated seven rooms--the seven stages of man?--and the masquerade serve to lend an unreality to the occasion of the party. Yet, when the "uninvited guest" arrives in the sixth room, the blue room, there is no defense against him. Prospero dies instantly in the seventh room, the red room, after accosting this agent of death as do the "throng of revelers."