He started home again, butthe agent went with him. In the train the agent murdered him, took themore essential papers, and threw his body from the carriage. Thatwould account for everything, would it not?"

  "Why had he no ticket?"

  "The ticket would have shown which station was nearest the agent'shouse. Therefore he took it from the murdered man's pocket."

  "Good, Lestrade, very good," said Holmes. "Your theory holds together.But if this is true, then the case is at an end. On the one hand, thetraitor is dead. On the other, the plans of the Bruce-Partingtonsubmarine are presumably already on the Continent. What is there forus to do?"

  "To act, Sherlock--to act!" cried Mycroft, springing to his feet. "Allmy instincts are against this explanation. Use your powers! Go to thescene of the crime! See the people concerned! Leave no stoneunturned! In all your career you have never had so great a chance ofserving your country."

  "Well, well!" said Holmes, shrugging his shoulders. "Come, Watson!And you, Lestrade, could you favour us with your company for an hour ortwo? We will begin our investigation by a visit to Aldgate Station.Good-bye, Mycroft. I shall let you have a report before evening, but Iwarn you in advance that you have little to expect."

  An hour later Holmes, Lestrade and I stood upon the Undergroundrailroad at the point where it emerges from the tunnel immediatelybefore Aldgate Station. A courteous red-faced old gentlemanrepresented the railway company.

  "This is where the young man's body lay," said he, indicating a spotabout three feet from the metals. "It could not have fallen fromabove, for these, as you see, are all blank walls. Therefore, it couldonly have come from a train, and that train, so far as we can trace it,must have passed about midnight on Monday."

  "Have the carriages been examined for any sign of violence?"

  "There are no such signs, and no ticket has been found."

  "No record of a door being found open?"

  "None."

  "We have had some fresh evidence this morning," said Lestrade. "Apassenger who passed Aldgate in an ordinary Metropolitan train about11:40 on Monday night declares that he heard a heavy thud, as of a bodystriking the line, just before the train reached the station. Therewas dense fog, however, and nothing could be seen. He made no reportof it at the time. Why, whatever is the matter with Mr. Holmes?"

  My friend was standing with an expression of strained intensity uponhis face, staring at the railway metals where they curved out of thetunnel. Aldgate is a junction, and there was a network of points. Onthese his eager, questioning eyes were fixed, and I saw on his keen,alert face that tightening of the lips, that quiver of the nostrils,and concentration of the heavy, tufted brows which I knew so well.

  "Points," he muttered; "the points."

  "What of it? What do you mean?"

  "I suppose there are no great number of points on a system such asthis?"

  "No; they are very few."

  "And a curve, too. Points, and a curve. By Jove! if it were only so."

  "What is it, Mr. Holmes? Have you a clue?"

  "An idea--an indication, no more. But the case certainly grows ininterest. Unique, perfectly unique, and yet why not? I do not see anyindications of bleeding on the line."

  "There were hardly any."

  "But I understand that there was a considerable wound."

  "The bone was crushed, but there was no great external injury."

  "And yet one would have expected some bleeding. Would it be possiblefor me to inspect the train which contained the passenger who heard thethud of a fall in the fog?"

  "I fear not, Mr. Holmes. The train has been broken up before now, andthe carriages redistributed."

  "I can assure you, Mr. Holmes," said Lestrade, "that every carriage hasbeen carefully examined. I saw to it myself."

  It was one of my friend's most obvious weaknesses that he was impatientwith less alert intelligences than his own.

  "Very likely," said he, turning away. "As it happens, it was not thecarriages which I desired to examine. Watson, we have done all we canhere. We need not trouble you any further, Mr. Lestrade. I think ourinvestigations must now carry us to Woolwich."

  At London Bridge, Holmes wrote a telegram to his brother, which hehanded to me before dispatching it. It ran thus:

  See some light in the darkness, but it may possibly flicker out.Meanwhile, please send by messenger, to await return at Baker Street, acomplete list of all foreign spies or international agents known to bein England, with full address.

  Sherlock.

  "That should be helpful, Watson," he remarked as we took our seats inthe Woolwich train. "We certainly owe Brother Mycroft a debt forhaving introduced us to what promises to be a really very remarkablecase."

  His eager face still wore that expression of intense and high-strungenergy, which showed me that some novel and suggestive circumstance hadopened up a stimulating line of thought. See the foxhound with hangingears and drooping tail as it lolls about the kennels, and compare itwith the same hound as, with gleaming eyes and straining muscles, itruns upon a breast-high scent--such was the change in Holmes since themorning. He was a different man from the limp and lounging figure inthe mouse-coloured dressing-gown who had prowled so restlessly only afew hours before round the fog-girt room.

  "There is material here. There is scope," said he. "I am dull indeednot to have understood its possibilities."

  "Even now they are dark to me."

  "The end is dark to me also, but I have hold of one idea which may leadus far. The man met his death elsewhere, and his body was on the ROOFof a carriage."

  "On the roof!"

  "Remarkable, is it not? But consider the facts. Is it a coincidencethat it is found at the very point where the train pitches and sways asit comes round on the points? Is not that the place where an objectupon the roof might be expected to fall off? The points would affectno object inside the train. Either the body fell from the roof, or avery curious coincidence has occurred. But now consider the questionof the blood. Of course, there was no bleeding on the line if the bodyhad bled elsewhere. Each fact is suggestive in itself. Together theyhave a cumulative force."

  "And the ticket, too!" I cried.

  "Exactly. We could not explain the absence of a ticket. This wouldexplain it. Everything fits together."

  "But suppose it were so, we are still as far as ever from unravellingthe mystery of his death. Indeed, it becomes not simpler but stranger."

  "Perhaps," said Holmes, thoughtfully, "perhaps." He relapsed into asilent reverie, which lasted until the slow train drew up at last inWoolwich Station. There he called a cab and drew Mycroft's paper fromhis pocket.

  "We have quite a little round of afternoon calls to make," said he. "Ithink that Sir James Walter claims our first attention."

  The house of the famous official was a fine villa with green lawnsstretching down to the Thames. As we reached it the fog was lifting,and a thin, watery sunshine was breaking through. A butler answeredour ring.

  "Sir James, sir!" said he with solemn face. "Sir James died thismorning."

  "Good heavens!" cried Holmes in amazement. "How did he die?"

  "Perhaps you would care to step in, sir, and see his brother, ColonelValentine?"

  "Yes, we had best do so."

  We were ushered into a dim-lit drawing-room, where an instant later wewere joined by a very tall, handsome, light-beared man of fifty, theyounger brother of the dead scientist. His wild eyes, stained cheeks,and unkempt hair all spoke of the sudden blow which had fallen upon thehousehold. He was hardly articulate as he spoke of it.

  "It was this horrible scandal," said he. "My brother, Sir James, was aman of very sensitive honour, and he could not survive such an affair.It broke his heart. He was always so proud of the efficiency of hisdepartment, and this was a crushing blow."

  "We had hoped that he might have given us some indications which wouldhave helped us to clear the matter up."

  "I assure y
ou that it was all a mystery to him as it is to you and toall of us. He had already put all his knowledge at the disposal of thepolice. Naturally he had no doubt that Cadogan West was guilty. Butall the rest was inconceivable."

  "You cannot throw any new light upon the affair?"

  "I know nothing myself save what I have read or heard. I have nodesire to be discourteous, but you can understand, Mr. Holmes, that weare much disturbed at present, and I must ask you to hasten thisinterview to an end."

  "This is indeed an unexpected development," said my friend when we hadregained the cab. "I wonder if the death was natural,