“I thought I might surprise you. Mycroft draws four hundred and fifty pounds a year, remains a subordinate, has no ambitions of any kind, will receive neither honour nor title, but remains the most indispensable man in the country.”

“But how?”

“Well, his position is unique. He has made it for himself. There has never been anything like it before, nor will be again. He has the tidiest and most orderly brain, with the greatest capacity for storing facts, of any man living. The same great powers which I have turned to the detection of crime he has used for this particular business. The conclusions of every department are passed to him, and he is the central exchange, the clearing-house, which makes out the balance. All other men are specialists, but his specialism is omniscience. We will suppose that a minister needs information as to a point which involves the Navy, India, Canada and the bimetallic question; he could get his separate advices from various departments upon each, but only Mycroft can focus them all, and say offhand how each factor would affect the other. They began by using him as a short-cut, a convenience; now he has made himself an essential. In that great brain of his everything is pigeon-holed and can be handed out in an instant. Again and again his word has decided the national policy. He lives in it. He thinks of nothing else save when, as an intellectual exercise, he unbends if I call upon him and ask him to advise me on one of my little problems. But Jupiter is descending to-day. What on earth can it mean? Who is Cadogan West, and what is he to Mycroft?”

“I have it,” I cried, and plunged among the litter of papers upon the sofa. “Yes, yes, here he is, sure enough! Cadogan West was the young man who was found dead on the Underground on Tuesday morning.”

Holmes sat up at attention, his pipe halfway to his lips.

“This must be serious, Watson. A death which has caused my brother to alter his habits can be no ordinary one. What in the world can he have to do with it? The case was featureless as I remember it. The young man had apparently fallen out of the train and killed himself. He had not been robbed, and there was no particular reason to suspect violence. Is that not so?”

“There has been an inquest,” said I, “and a good many fresh facts have come out. Looked at more closely, I should certainly say that it was a curious case.”

“Judging by its effect upon my brother, I should think it must be a most extraordinary one.” He snuggled down in his armchair. “Now, Watson, let us have the facts.”

“The man’s name was Arthur Cadogan West. He was twenty-seven years of age, unmarried, and a clerk at Woolwich Arsenal.”

“Government employ. Behold the link with Brother Mycroft!”

“He left Woolwich suddenly on Monday night. Was last seen by his fiancee, Miss Violet Westbury, whom he left abruptly in the fog about 7:30 that evening. There was no quarrel between them and she can give no motive for his action. The next thing heard of him was when his dead body was discovered by a plate-layer named Mason, just outside Aldgate Station on the Underground system in London.”

“When?”

“The body was found at six on the Tuesday morning. It was lying wide of the metals upon the left hand of the track as one goes eastward, at a point close to the station, where the line emerges from the tunnel in which it runs. The head was badly crushed - an injury which might well have been caused by a fall from the train. The body could only have come on the line in that way. Had it been carried down from any neighbouring street, it must have passed the station barriers, where a collector is always standing. This point seems absolutely certain.”