“A girl of strong character.”

“Yes, but she is a good sort, or I am mistaken. She and her brother are the only children of an iron-master somewhere up Northumberland way. He got engaged to her when travelling last winter, and she came down to be introduced to his people, with her brother as escort. Then came the smash, and she stayed on to nurse her lover, while brother Joseph, finding himself pretty snug, stayed on, too. I’ve been making a few independent inquiries, you see. But to-day must be a day of inquiries.”

“My practice- -” I began.

“Oh, if you find your own cases more interesting than mine- -” said Holmes with some asperity.

“I was going to say that my practice could get along very well for a day or two, since it is the slackest time in the year.”

“Excellent,” said he, recovering his good-humour. “Then we’ll look into this matter together. I think that we should begin by seeing Forbes. He can probably tell us all the details we want until we know from what side the case is to be approached.”

“You said you had a clue?”

“Well, we have several, but we can only test their value by further inquiry. The most difficult crime to track is the one which is purposeless. Now this is not purposeless. Who is it who profits by it? There is the French ambassador, there is the Russian, there is whoever might sell it to either of these, and there is Lord Holdhurst.”

“Lord Holdhurst!”

“Well, it is just conceivable that a statesman might find himself in a position where he was not sorry to have such a document accidentally destroyed.”

“Not a statesman with the honourable record of Lord Holdhurst?”

“It is a possibility and we cannot afford to disregard it. We shall see the noble lord to-day and find out if he can tell us anything. Meanwhile I have already set inquiries on foot.”

“Already?”

“Yes, I sent wires from Woking station to every evening paper in London. This advertisement will appear in each of them.”

He handed over a sheet torn from a notebook. On it was scribbled in pencil:

£10 reward. The number of the cab which dropped a fare at or about the door of the Foreign Office in Charles Street at quarter to ten in the evening of May 23d. Apply 221B, Baker Street.

“You are confident that the thief came in a cab?”

“If not, there is no harm done. But if Mr. Phelps is correct in stating that there is no hiding-place either in the room or the corridors, then the person must have come from outside. If he came from outside on so wet a night, and yet left no trace of damp upon the linoleum, which was examined within a few minutes of his passing, then it is exceedingly probable that he came in a cab. Yes, I think that we may safely deduce a cab.”

“It sounds plausible.”

“That is one of the clues of which I spoke. It may lead us to something. And then, of course, there is the bell - which is the most distinctive feature of the case. Why should the bell ring? Was it the thief who did it out of bravado? Or was it someone who was with the thief who did it in order to prevent the crime? Or was it an accident? Or was it- -?” He sank back into the state of intense and silent thought from which he had emerged; but it seemed to me, accustomed as I was to his every mood, that some new possibility had dawned suddenly upon him.

It was twenty past three when we reached our terminus, and after a hasty luncheon at the buffet we pushed on at once to Scotland Yard. Holmes had already wired to Forbes, and we found him waiting to receive us -a small, foxy man with a sharp but by no means amiable expression. He was decidedly frigid in his manner to us, especially when he heard the errand upon which we had come.