Prince Prospero decides to respond to the frightening epidemic of the Red Death sweeping through the kingdom by holding a lavish masquerade ball and inviting the wealthiest inhabitants of the region. One of the guests is cloaked and masked as the Grim Reaper. This angers Prince Prospero, who wanted his ball to be a festive occasion. This mysterious guest causes discomfort and a vague feeling of horror among the guests.
The Prince had arranged for seven chambers of his palace to be decorated in rich colors, with draperies and furnishings matching the singular wall colors, with the last chamber of the seven being two colors: black walls and draperies with blood red windows. This last room gave the guests a chilling feeling of dread and many of them cannot even enter it without feeling unwell. It is in this last chamber where Prince Proposer meets his demise.
This occurs after he pursues the mysterious cloaked and masked figure. He finally corners him in that seventh chamber and raises a dagger; but then the prince collapses and dies. The guests learn the the mysterious figure does not even exist under the cloak and mask, and they too collapse and die, all consumed by the Red Death which Prince Prospero had hoped to shelter them all from.