The striking of the clock in the seventh room of the castle of Prince Prospero produces a harrowing effect upon the guests as it arrests both the musicians and dancers, and it reminds them of the passage of time. When the clock strikes midnight, the revelers have an even keener awareness of the marking of an end, especially when they become aware of a ghastly masked figure.
After his dominions become decimated by the "Red Death," the supercilious Prince Prospero summons his courtiers to join him at one of his resplendent castles and leave the "external world to take care of itself." Within the castle are clowns, poets, musicians, and ballet dancers to magnificently entertain these guests. Outside resides the "Red Death."
Near the end of six months, the Prince decides to entertain his many guests with a masquerade of great splendor. This masque is to be held in seven rooms of an imperial suite. Each room is situated at angles so that there is no view from one room to the next; also, these rooms are all of different colors and the windows are tinted to match the walls. Only the seventh room, a room shrouded in black velvet tapestries that cover the ceiling and drape down walls onto the black carpet, has windows of a different color: The panes of this room are a deep blood red. This room also has an imposing clock made of ebony that stands against the western wall.
...the brazen lungs of the clock [emit] so peculiar a note and emphasis that at each lapse of an hour, the musicians of the orchestra were constrained to pause momentarily...to hearken to the sound;...thus the waltzers perforce ceased their evolutions; and there was brief disconcert of the whole gay company....
The effect of this clock is so profound that even the giddiest is silent and pale and confused. But, when the tolling of the clock ceases, the revelers resume their laughter, though softer. As the hour strikes each time, the revelers appear more tremulous and disconcerted. Somehow in this room as the clock tolls the final hour, the revelers appear grotesque in the darkness and glare and glitter. It seems as though a "multitude of dreams" stalks the rooms until the presence of a strange masked figure is noticed because his costume has exceeded any decorum: He is "shrouded from head to foot in the habiliments of the grave."
Enraged that such an interloper has entered his castle, the Prince challenges this ghastly figure: "Who dares insult us with this blasphemous mockery?" he calls out as he hurries from the blue room through the other chambers. He holds up a dagger, but before Prospero can use it, he utters a sharp cry. Suddenly, the dagger falls to the floor and, instantly afterwards, so does the body of the dead Prospero. The final hour of life has struck as, one by one, the revelers also die. Nothing of the intruder remains but the wrappings of the...
grave and the "corpse-like mask."