How does Prince Prospero and his friends escape from the Red Death?
Prince Prospero and his "thousand hale and light-hearted friends" do not escape from the Red Death completely. They only manage to avoid the plague for a short while by taking the most elaborate precautions to keep themselves in a sort of luxurious quarantine. They are only concerned about saving themselves and care nothing for the humble masses who are being relentlessly slaughtered by this mysterious plague. The Prince and his thousand guests pass the time by engaging in what resembles an ongoing party, such as was the general spirit at Versailles in the time of Louis XVI and Marie Antoinette. Poe describes the precautions that Prince Prospero believed would be sufficient to protect himself and all his privileged retinue from the scourge that was gradually killing off everyone else in the kingdom.
When his dominions were half depopulated, he summoned to his presence a thousand hale and light-hearted friends from among the knights and dames of his court, and with these retired to the deep seclusion of one of his castellated abbeys....A strong and lofty wall girdled it in. This wall had gates of iron. The courtiers, having entered, brought furnaces and massy hammers and welded the bolts. They resolved to leave means neither of ingress or egress to the sudden impulses of despair or of frenzy from within. The abbey was amply provisioned. With such precautions the courtiers might bid defiance to contagion. The external world could take care of itself.
The whole point of Poe's parable is that death is inescapable. No matter how rich and important a man may be, death will find him out and take him away along with all the poorest and most wretched members of society. Poe personifies the Red Death as a tall, gaunt figure who appears at a masked ball dressed in a blood-spattered costume to represent the embodiment of the Red Death. How this uninvited guest managed to get inside the castle is not explained. Evidently he had the ability to walk through walls and pass through gates of iron. First the "spectral image" claims the life of Prince Prospero. Then:
...one by one dropped the revellers in the blood-bedewed halls of their revel, and died each in the despairing posture of his fall.