For the next two days Mark and I worked out our plans. You understand by now that our aims were not identical. Mark’s endeavour was that his deception should last for, say, a couple of hours; mine that it should go to the grave with him. He had only to deceive Miss Norris and the other guests; I had to deceive the world. When he was dressed up as Robert, I was going to kill him. Robert would then be dead, Mark (of course) missing. What could anybody think but that Mark had killed Robert? But you see how important it was for Mark to enter fully into his latest (and last) impersonation. Half-measures would be fatal.