Prince Prospero is introduced as the ruler of the "dominions" ravaged by the Red Death.
Prospero reacts to the plague by fleeing to his "castellated abbey" with a thousand of his favorite knights and ladies.
About six months into his stay, Prince Prospero decides to throw an elaborate masquerade ball in a suite of seven colored rooms. He designed it himself, and it's so weird you might even think he was crazy.
Prince Prospero's masquerade is a huge hit. Then, at midnight, the Prince, who's hanging out in the blue room, sees a new face in the crowd. Oh the bad taste! Somebody is dressed up as a victim of the Red Death.
Prospero is outraged, and orders the guest to be seized and unmasked. But nobody has the courage to approach him, including Prospero himself. The strange and offensive guest just goes on making his way through the rooms.
Prospero finally gets up the courage. He draws his dagger and runs after the interloper.
Prospero reaches the Red Death masquerader at the edge of the black room. The masquerader whirls around to face him, and…
That's not a masquerader, that's actually the Red Death. Prospero dies.