Cayley had been in the hall when Robert was shown into the office. The servant goes off to look for Mark, and Cayley goes on with his book. Mark comes down the stairs, warns Cayley to stand by in case he is wanted, and goes to meet his brother. What does Cayley expect? Possibly that he won’t be wanted at all; possibly that his advice may be wanted in the matter, say, of paying Robert’s debts, or getting him a passage back to Australia; possibly that his physical assistance may be wanted to get an obstreperous Robert out of the house. Well, he sits there for a moment, and then goes into the library. Why not? He is still within reach, if wanted. Suddenly he hears a pistol-shot. A pistol-shot is the last noise you expect to hear in a country-house; very natural, then, that for the moment he would hardly realize what it was. He listens—and hears nothing more. Perhaps it wasn’t a pistol-shot after all. After a moment or two he goes to the library door again. The profound silence makes him uneasy now. _Was_ it a pistol-shot? Absurd! Still—no harm in going into the office on some excuse, just to reassure himself. So he tries the door—and finds it locked! What are his emotions now? Alarm, uncertainty. Something is happening. Incredible though it seems, it must have been a pistol-shot. He is banging at the door and calling out to Mark, and there is no answer. Alarm—yes. But alarm for whose safety? Mark’s, obviously. Robert is a stranger; Mark is an intimate friend. Robert has written a letter that morning, the letter of a man in a dangerous temper. Robert is the tough customer; Mark the highly civilized gentleman. If there has been a quarrel, it is Robert who has shot Mark. He bangs at the door again. Of course, to Antony, coming suddenly upon this scene, Cayley’s conduct had seemed rather absurd, but then, just for the moment, Cayley had lost his head. Anybody else might have done the same. But, as soon as Antony suggested trying the windows, Cayley saw that that was the obvious thing to do. So he leads the way to the windows—the longest way. Why? To give the murderer time to escape? If he had thought then that Mark was the murderer, perhaps, yes. But he thinks that Robert is the murderer. If he is not hiding anything, he _must_ think so. Indeed he says so, when he sees the body; “I was afraid it was Mark,” he says, when he finds that it is Robert who is killed. No reason, then, for wishing to gain time. On the contrary, every instinct would urge him to get into the room as quickly as possible, and seize the wicked Robert. Yet he goes the longest way round. Why? And then, why _run?_