The central theme in "The Masque of the Red Death" is the inevitable, or perhaps more accurately, the inescapable nature, of death. Prospero and his companions attempt to shut themselves off from the rest of the world in an attempt to avoid the horrible plague (the "red death") that is ravaging the countryside. He is able to do this, of course, because he is wealthy and powerful. But even his money and influence cannot save him from Death, who shows up in human form, ostensibly costumed as a corpse, at the masque he stages inside the castle. In the end, the Prince and his followers tried to avoid Death, who destroys all of them:
And now was acknowledged the presence of the Red Death. ... like a thief in the night. And one by one dropped the revellers in the blood-bedewed halls ... and died each in the despairing posture of his fall. And the life of the ebony clock went out .... And the flames of the tripods expired. And Darkness and Decay and the Red Death held illimitable dominion over all.