"Why not?" I asked.

"Why not? It is as if you met a tramcar coming down a country lane. Mycroft has his rails and he runs on them. His Pall Mall lodgings, the Diogenes Club, Whitehall – that is his cycle. Once, and only once, he has been here. What upheaval can possibly have derailed him?"

"Does he not explain?"

Holmes handed me his brother's telegram.

Must see you over Cadogan West. Coming at once.

MYCROFT.

"Cadogan West? I have heard the name."

"It recalls nothing to my mind. But that Mycroft should break out in this erratic fashion! A planet might as well leave its orbit. By the way, do you know what Mycroft is?"

I had some vague recollection of an explanation at the time of the Adventure of the Greek Interpreter. "You told me that he had some small office under the British government."

Holmes chuckled. "I did not know you quite so well in those days. One has to be discreet when one talks of high matters of state. You are right in thinking that he is under the British government. You would also be right in a sense if you said that occasionally he is the British government."

"My dear Holmes!"

"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 honor 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 clearinghouse, which makes out the balance. All other men are specialists, but his specialty 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 pigeonholed 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 today. 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 neighboring street, it must have passed the station barriers, where a collector is always standing. This point seems absolutely certain."

"Very good. The case is definite enough. The man, dead or alive, either fell or was precipitated from a train. So much is clear to me. Continue."

"The trains which traverse the lines of rail beside which the body was found are those which run from west to east, some being purely Metropolitan, and some from Willesden and outlying junctions. It can be stated for certain that this young man when he met his death, was traveling in this direction at some late hour of the night, but at what point he entered the train it is impossible to state."

"His ticket, of course, would show that."

"There was no ticket in his pockets."

"No ticket! Dear me, Watson, this is really very singular. According to my experience it is not possible to reach the platform of a Metropolitan train without exhibiting one's ticket. Presumably, then, the young man had one. Was it taken from him in order to conceal the station from which he came? It is possible. Or did he drop it in the carriage? That also is possible. But the point is of curious interest. I understand that there was no sign of robbery?"

"Apparently not. There is a list here of his possessions. His purse contained two pounds fifteen. He had also a checkbook on the Woolwich branch of the Capital and Counties Bank. Through this his identity was established. There were also two dress-circle tickets for the Woolwich Theatre, dated for that very evening. Also a small packet of technical papers."

Holmes gave an exclamation of satisfaction. "There we have it at last, Watson! British government – Woolwich. Arsenal – technical papers – Brother Mycroft, the chain is complete. But here he comes, if I am not mistaken, to speak for himself."

A moment later the tall and portly form of Mycroft Holmes was ushered into the room. Heavily built and massive, there was a suggestion of uncouth physical inertia in the figure, but above this unwieldy frame there was perched a head so masterful in its brow, so alert in its steel-gray, deep-set eyes, so firm in its lips, and so subtle in its play of expression, that after the first glance one forgot the gross body and remembered only the dominant mind.

At his heels came our old friend Lestrade, of Scotland Yard – thin and austere. The gravity of both their faces foretold some weighty quest. The detective shook hands without a word. Mycroft Holmes struggled out of his overcoat and subsided into an armchair.

"A most annoying business, Sherlock," said he. "I extremely dislike altering my habits, but the powers that be would take no denial. In the present state of Siam it is most awkward that I should be away from the office. But it is a real crisis. I have never seen the Prime Minister so upset. As to the Admiralty – it is buzzing like an overturned beehive. Have you read up the case?"