The climax of the comes after the Red Death arrives at Prince Prospero's masked ball. Prospero had locked himself and a thousand of his closest friends inside an abbey in order to escape the disease the plagued his land. During the sixth month of quarantine, Prospero decided to throw a lavish party to celebrate having escaped the Red Death. During the party, however, Prospero spies someone whom he believes to be one of his guests who had the audacity to come to the party dressed in a Red Death costume. He chases the figure from room to room until they reach the black room in the western part of the hall. There, the figure turns towards Prospero and the Prince falls to the floor dead (climax). He could not escape Death no matter how well he tried to barricade himself from the world.
The climax of this story occurs after Prospero has ordered his revelers to unmask the mysterious stranger who has appeared in their midst. The rising action has been the movement of Prospero and his guests through each of the different colored rooms, except for the very last room which frightens them all. Upon seeing this unknown "guest" in his horrific costume of death and blood, Prospero orders his other guests to grab this "blasphemer" and unmask him so he can be punished. The guests are too frightened to, so finally Prospero has to do it himself, after chasing the figure into the final room. The climax, then, is the turning of the figure to face Prospero, who now learns that the uninvited guest is the Red Death itself, which is there to kill Prospero and all of his revelers.
thanks for the great answer!! :]