“Never mind for the time being—but if you look carefully at where I’m standing—you’ll be able to see for yourself.” Peter looked—but saw nothing to solve his own difficulty. He shook his head, as though to give point to his failure to grasp Anthony’s idea. The next words the latter spoke rather startled him. “Stewart stood where you are standing and fired in the direction of where I am standing—then something happened that caused him to put his revolver back in the pocket of his dressing-gown—the left-hand pocket, remember—and to take a rather changed view of the situation in which he found himself.” “What was that?” demanded Peter. “_He recognized the interloper—the interloper who afterwards murdered him._” “Why then,” countered Peter instantly, “didn’t he recognize him at first—before he fired the shot? You either know or don’t know a person—it isn’t as though Stewart fired from a distance—you say yourself that he fired from the doorway only a few feet away—when he entered the room—the fact that he _did_ fire in that way seems to me to show conclusively that he _didn’t_ know the person—that he fired at a stranger. You don’t blaze away with a revolver at anybody you happen to see—regardless of consequences.” He lit a cigarette with the air of a man that defies contradiction. “An excellent piece of reasoning on your part,” smiled Anthony, “but there’s one little possibility that I fear you may have been tempted to overlook.” “What’s that?” retorted Peter. “I’m not blaming you, my dear chap. I overlooked it myself in the first place; _supposing the conditions changed_.” Peter wrinkled his brow. “Conditions,” he said, in a puzzled kind of way, “what conditions do you mean?” “The conditions of the room!” Anthony watched Peter’s mystified expression. “As I said just now, Daventry, I was slow myself to pick up the crucial point. When Stewart fired his shot—he fired _in the dark_. When the intruder disclosed his identity, Stewart put his revolver away—he felt safe. So safe that he put it away in his left-hand pocket—a right-handed man doesn’t do that if he wants to use it again. And unhappily, events proved that his faith in the situation brought about his death—that was why I told you to look where I was standing.” He pointed to the wall to the right of the bookcase directly facing the doorway. Peter’s eyes followed the direction of his finger. “The electric light switch?” he queried.