The deaths of Prince Prospero and his guests are totally unexpected. The Prince had thought he and his courtiers could escape the Red Death by seculuding themselves in a huge abbey surrounded by a high wall and welding the gates shut so that no one could leave or enter. The huge building was provisioned with everything they needed to survive for as long as they considered necessary. They all spent their time being entertained in a manner reminiscent of Louis XIV at the Palace of Versailles. The story is an allegory illustrating that death is inescapable but people look for distractions and avoid thinking about it. That is why Death come unexpectedly at the end. The large rooms with their different colors are probably intended to represent the different stages of life leading inevitably to death. The sudden extinction of all those reveling people probably comes as a surprise to the reader as well as to the Prince and his courtiers.