“How do I know that they are lying? Because it is a clumsy fabrication which simply could not be true. Consider! According to the story given to us, the assassin had less than a minute after the murder had been committed to take that ring, which was under another ring, from the dead man’s finger, to replace the other ring - a thing which he would surely never have done - and to put that singular card beside his victim. I say that this was obviously impossible.

“You may argue - but I have too much respect for your judgment, Watson, to think that you will do so - that the ring may have been taken before the man was killed. The fact that the candle had been lit only a short time shows that there had been no lengthy interview. Was Douglas, from what we hear of his fearless character, a man who would be likely to give up his wedding ring at such short notice, or could we conceive of his giving it up at all? No, no, Watson, the assassin was alone with the dead man for some time with the lamp lit. Of that I have no doubt at all.

“But the gunshot was apparently the cause of death. Therefore the shot must have been fired some time earlier than we are told. But there could be no mistake about such a matter as that. We are in the presence, therefore, of a deliberate conspiracy upon the part of the two people who heard the gunshot - of the man Barker and of the woman Douglas. When on the top of this I am able to show that the blood mark on the windowsill was deliberately placed there by Barker, in order to give a false clue to the police, you will admit that the case grows dark against him.

“Now we have to ask ourselves at what hour the murder actually did occur. Up to half-past ten the servants were moving about the house; so it was certainly not before that time. At a quarter to eleven they had all gone to their rooms with the exception of Ames, who was in the pantry. I have been trying some experiments after you left us this afternoon, and I find that no noise which MacDonald can make in the study can penetrate to me in the pantry when the doors are all shut.

“It is otherwise, however, from the housekeeper’s room. It is not so far down the corridor, and from it I could vaguely hear a voice when it was very loudly raised. The sound from a shotgun is to some extent muffled when the discharge is at very close range, as it undoubtedly was in this instance. It would not be very loud, and yet in the silence of the night it should have easily penetrated to Mrs. Allen’s room. She is, as she has told us, somewhat deaf; but none the less she mentioned in her evidence that she did hear something like a door slamming half an hour before the alarm was given. Half an hour before the alarm was given would be a quarter to eleven. I have no doubt that what she heard was the report of the gun, and that this was the real instant of the murder.

“If this is so, we have now to determine what Barker and Mrs. Douglas, presuming that they are not the actual murderers, could have been doing from quarter to eleven, when the sound of the shot brought them down, until quarter past eleven, when they rang the bell and summoned the servants. What were they doing, and why did they not instantly give the alarm? That is the question which faces us, and when it has been answered we shall surely have gone some way to solve our problem.”

“I am convinced myself,” said I, “that there is an understanding between those two people. She must be a heartless creature to sit laughing at some jest within a few hours of her husband’s murder.”