“We may form some conception as to the motives of the crime. It is, as I gather from your original remarks, an inexplicable, or at least an unexplained, murder. Now, presuming that the source of the crime is as we suspect it to be, there might be two different motives. In the first place, I may tell you that Moriarty rules with a rod of iron over his people. His discipline is tremendous. There is only one punishment in his code. It is death. Now we might suppose that this murdered man—this Douglas whose approaching fate was known by one of the arch-criminal’s subordinates—had in some way betrayed the chief. His punishment followed, and would be known to all—if only to put the fear of death into them.”

“Well, that is one suggestion, Mr. Holmes.”

“The other is that it has been engineered by Moriarty in the ordinary course of business. Was there any robbery?”

“I have not heard.”

“If so, it would, of course, be against the first hypothesis and in favour of the second. Moriarty may have been engaged to engineer it on a promise of part spoils, or he may have been paid so much down to manage it. Either is possible. But whichever it may be, or if it is some third combination, it is down at Birlstone that we must seek the solution. I know our man too well to suppose that he has left anything up here which may lead us to him.”

“Then to Birlstone we must go!” cried MacDonald, jumping from his chair. “My word! it’s later than I thought. I can give you, gentlemen, five minutes for preparation, and that is all.”

“And ample for us both,” said Holmes, as he sprang up and hastened to change from his dressing gown to his coat. “While we are on our way, Mr. Mac, I will ask you to be good enough to tell me all about it.”

“All about it” proved to be disappointingly little, and yet there was enough to assure us that the case before us might well be worthy of the expert’s closest attention. He brightened and rubbed his thin hands together as he listened to the meagre but remarkable details. A long series of sterile weeks lay behind us, and here at last there was a fitting object for those remarkable powers which, like all special gifts, become irksome to their owner when they are not in use. That razor brain blunted and rusted with inaction.