Gregory Porlock's party was a very successful one - from Gregory's point of view. He was in the highest of spirits, and the fact that his guests were obviously not in a party mood only added to his enjoyment. He knew they all had good reason to fear and dislike him, and it amused him to play the part of the genial host, and to watch each of his visitors trying to act the part of a gay and carefree guest for the benefit of all the others. Gregory never knew that one of his visitors played two roles that evening, that someone doubled the part of guest and murderer, for in that drama Gregory Porlock was cast for a different role.