The second woman was Grizelda Magdalena Hoffmannstal, although it was not certain that this was her real name. She styled herself the Princess Zelda, but the provenance of her title was a matter of some debate, as, indeed, were her antecedents in general. She herself never revealed anything of her past, and the mystery that seemed to surround her inevitably led to wild conjecture and an air of glamour. This she appeared to enjoy, and she certainly never did anything to dispel it. Some said that she was enormously wealthy, and it was undoubtedly true that she lived in a fashion that bespoke great wealth. But it is doubtful if she ever paid out a penny from her own purse, for she was never lacking for gentlemen admirers, who were only too willing to do whatever might be necessary to gain her favour. Needless to say, the female half of London Society took a somewhat less favourable view of the Princess Zelda, but on the whole the Press ignored this point of view. There were also rumours in some quarters that the princess was a spy, in the pay of several foreign governments at once and in London only to work mischief, but little credence was given to this view. Sherlock Holmes, however, averred on more than one occasion that the Princess Zelda was undoubtedly the most dangerous woman in London. This struck me at the time as a somewhat exaggerated claim, but as I had found in the past that Holmes’s opinions invariably proved nearer to the mark than those expressed in the public prints, I reserved my opinion.

It was a cold evening, a few days before Christmas. It had been snowing lightly since early afternoon and now, in the still evening, a blanket of white covered the streets and houses. Sherlock Holmes had drawn back the curtains and gazed for some time at the chilly scene outside. Then he had perched himself on a chair by the window, taken up his violin and, for the best part of an hour, played a selection of Christmas carols. At length, he put down his bow and turned to where I was sitting by the blazing fire.

“It appears,” he remarked, “that even the world of villainy is honouring the forthcoming holiday season. I have heard nothing of criminal interest since the beginning of the week.”

“That is surely a cause for celebration rather than otherwise,” I returned.

My companion chuckled. “Perhaps so,” said he, “but I cannot help feeling that if plotters and criminals stay their hand at this time of year, they are undoubtedly overlooking a fine opportunity. Now is the very time they should strike, when the world of honest citizens has lowered its guard. It is certainly the way I should be thinking, were I a criminal.”

“No doubt,” I responded in some amusement. “But the season has its disadvantages for the criminal, too. Travel is difficult at this time of the year and train services are often disrupted. Having perpetrated his villainy, it might prove difficult for the criminal to make his escape.”

“But he should turn that very fact to his own advantage,” insisted my friend. “He should so time his crime that he escapes by the very last train before Christmas, knowing that before the authorities can get upon his trail they will have lost a whole day!”

Thus we discussed the subject back and forth for some time, our discussion warmed by the occasional tot of brandy. Outside, the snow began to fall again, and I was remarking on the strange, unnatural silence that had descended upon the great city when the sound of a carriage approaching from the direction of Oxford Street came to my ears.

“Urgent business, one must suppose, to bring anyone out on such a night,” remarked Holmes, glancing from the window. “Halloa! This may be interesting, Watson! The carriage is stopping at our door.”

There came a loud jangling at the doorbell, followed moments later by rapid footsteps upon the stair. Then our door was flung open and a strongly built young man in the uniform of a military officer burst unannounced into the room. His face was as white as the snow through which he had travelled, his eyes were wide open and staring, and his bloodless lip quivered with emotion. For a moment he looked wildly about him, his face twitching uncontrollably.

“May we be of assistance?” said Holmes.

“Mr Holmes!” cried our visitor, removing his cap. “Thank the Lord you are here!”

“My dear sir,” said Holmes, taking his cap, leading him to the fireside chair and pressing him down into it. “Pray calm yourself! A nip of brandy might be helpful, Watson, if you would be so good!”

The soldier threw back his head and downed the glass at a gulp, and a flush of colour came to his pallid cheeks. A second later, an incoherent torrent of Words poured from his lips.

“The situation is utterly desperate!” he cried, looking from one to the other of us. “I am ruined! The country is ruined! Whatever can I do?” Then he plunged his head into his hands and began to moan softly to himself.

I refilled his glass and pressed him to take a sip, and he calmed a little.

“Captain Armstrong!” said Holmes in a tone of authority, and the soldier looked up sharply. “Captain Walter Armstrong of the Durham Light Infantry! Your name and regiment are written in your cap,” he explained as the other stared at him in surprise. “You are a long way from home, sir. Pray, tell us what has happened to reduce you to this state! Quickly, man! If the situation is as urgent as your manner suggests, every moment you despair is a moment lost!”

Our visitor responded to my friend’s masterful manner, and slowly, by degrees, regained a grip on his emotions. He drained what remained of his brandy and began to describe to us the events that had brought him to our door.

“I am a captain with the Durham, as you say,” he explained, “but I have been seconded to the staff of the War Office on special duties for the last nine months. You performed a great service for our department last year, so I have heard, when Major Colefax was in charge, which is why I thought of you this evening, in my hour of desperation.”

“Ah!” said Holmes. “Major Colefax! That makes matters a little clearer. To explain to you who these gentlemen are, Watson, it is probably sufficient to say that their duties are paid for out of the so-called ‘Secret Service Fund’, which is so regularly the subject of questions and complaints in Parliament. You may speak freely before Dr Watson, Captain Armstrong. Nothing you say will pass beyond the walls of this room.”

“Very well,” said Armstrong. “I can tell you in a few words what has happened. The head of the department now is Major Lavelle. This morning, he left for Portsmouth, where he is staying overnight, leaving me in charge in his absence. For most of the day I have been supervising Norton, one of our clerks, who has been copying out a report on the Baltic question for the Prime Minister. Earlier this evening, I went to see Commander Fordyce at the Admiralty, and left Norton writing at his desk. When I returned, just before eight o’clock, I asked the man at the door if there had been any callers, and was informed that no one had passed in or out since I had left, two hours previously. I entered the office and found Norton still scribbling away furiously, but on the last page, which he completed a minute later.

“‘That has been quite a task for you,’ I remarked, thanking him for staying late to complete it.

“‘Yes, sir,’ he returned. ‘I would have finished it earlier, but I have not been feeling well.’

“‘I am sorry to hear that,’ said I. ‘You get along home now and have an early night.’

“After he had left, I glanced over what he had written, then unlocked the safe to place the papers in there until Major Lavelle’s return. It at once struck me that there was something different about the disposition of the papers in the safe. For a long moment I stared at them, then I saw what was amiss. The largest pile, containing complete details of the new codes and ciphers which have recently been issued to the Army, was not quite as I had left it. It occupied the same position in the safe, but whereas I had left it at a slightly crooked angle to the pile of documents next to it, it was now perfectly straight. I have a very precise and accurate memory for such things, and have trained myself to observe such small discrepancies.”