“Very likely,” said he, turning away. “As it happens, it was not the carriages which I desired to examine. Watson, we have done all we can here. We need not trouble you any further, Mr. Lestrade. I think our investigations must now carry us to Woolwich.”

At London Bridge, Holmes wrote a telegram to his brother, which he handed 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, a complete list of all foreign spies or international agents known to be in England, with full address.

SHERLOCK.

“That should be helpful, Watson,” he remarked as we took our seats in the Woolwich train. “We certainly owe Brother Mycroft a debt for having introduced us to what promises to be a really very remarkable case.”

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

“There is material here. There is scope,” said he. “I am dull indeed not 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 lead us far. The man met his death elsewhere, and his body was on the roof of a carriage.”

“On the roof!”

“Remarkable, is it not? But consider the facts. Is it a coincidence that it is found at the very point where the train pitches and sways as it comes round on the points? Is not that the place where an object upon the roof might be expected to fall off? The points would affect no object inside the train. Either the body fell from the roof, or a very curious coincidence has occurred. But now consider the question of the blood. Of course, there was no bleeding on the line if the body had bled elsewhere. Each fact is suggestive in itself. Together they have a cumulative force.”

“And the ticket, too!” I cried.

“Exactly. We could not explain the absence of a ticket. This would explain it. Everything fits together.”

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

“Perhaps,” said Holmes thoughtfully, “perhaps.” He relapsed into a silent reverie, which lasted until the slow train drew up at last in Woolwich Station. There he called a cab and drew Mycroft’s paper from his pocket.

“We have quite a little round of afternoon calls to make,” said he. “I think that Sir James Walter claims our first attention.”

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

“Sir James, sir!” said he with solemn face. “Sir James died this morning.”

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

“Perhaps you would care to step in, sir, and see his brother, Colonel Valentine?”

“Yes, we had best do so.”