General Septimus Octavian Nuno Pellinsky, Count of Kosadam, Hereditary Guardian of the Monks of St Stephen and Adjutant General to the House of Capricorn, had almost as many titles on his card as he had brass buttons on his uniform, and he was shown into Mr Holmes’s study with all the promptitude his dramatic presence seemed to demand. As well as that dazzling array of colours, he carried with him a strong scent of pipe tobacco, a hint of fashionable cologne and an undeniable air of grandeur. I have ushered more than one great statesman into Mr Holmes’s presence, as well as some of the highest-ranking lords and ladies in the land, but there’s no denying that few of them filled the room in quite the same way as General Pellinsky.

It was perhaps something of a relief to me that my employers seemed no less startled than I had been by the appearance of our visitor. Dr Watson, clearly taken aback by such great quantities of ribbon and braid, rose hastily from his armchair and for the briefest of moments appeared ready to stand to attention; and even Mr Holmes, though less obviously inclined to salute, lowered his pipe to his waist and noticeably hesitated before offering the usual words of welcome.

Introductions followed, however, and the general was offered a seat, then whisky and tobacco, and was made as comfortable as possible in an armchair slightly too small for him. Once I had moved the drinks tray closer to Dr Watson, there was no excuse for me to linger, so I bobbed a little curtsy and retreated, taking with me an empty beer bottle hastily retrieved from one end of the mantelpiece and some screwed-up pages of The Times, which Dr Watson, to amuse himself, had been shying at the wastepaper basket. No room containing General Pellinsky ever really looked tidy, though; his great frame still sat awkwardly in its seat, and his uniform clashed with the rug.

I didn’t retreat very far. My chores were done for the day, but there was no prospect of going to bed while our guest remained in the house, and little point in making myself too comfortable downstairs when the bell might summon me back at any minute. So instead of joining Mrs Hudson, who was writing letters at the kitchen table next to a rather fine glass of port, I retired to the silver cupboard, where there were always knives to polish and spoons to put away, and where a large, engraved plate of dubious taste, presented to Mr Holmes by the grateful son of an anxious archbishop, was sadly tarnished and awaiting some attention.

I must confess, however, that I was not entirely motivated by an urge to polish cutlery. The silver cupboard was not really a cupboard at all, but a very small room lined with deep shelves, and there was just enough space in there for a diligent housemaid who tucked in her elbows to get to work with a soft cloth. It also happened to be directly opposite Mr Holmes’s study, and positioned in such a way that if the study door was left only a little open, and if the door of the silver cupboard was not quite closed, anyone engaging with the soup spoons was afforded a surprisingly clear view into the other room. In addition, voices carried quite clearly between the two rooms, so that a young girl going about her chores in one couldn’t help but overhear a great deal of what was said in the other.

In my defence, it hadn’t taken my employer very long to discover this acoustic anomaly, and yet he had never seemed greatly exercised by it. While his visitors would no doubt have been appalled by the idea that their discussions might be overheard, Mr Holmes seemed to find a certain wry amusement in the possibility, believing firmly that the better Mrs Hudson and I understood his activities and requirements, the more efficiently we could cater to his needs. To Mr Holmes, discretion and confidentiality were quite different things, and I had seen for myself that clients were prepared to overlook a great many eccentricities if they contributed to a satisfactory outcome.

Whether or not General Pellinsky was one such client was hard to say, but his pale demeanour, and the distress in his voice, suggested that he was in no mood to quibble about the great detective’s unusual domestic habits. When he spoke, it was in the slightly too perfect English of one who is not a native speaker.

‘You will forgive me, sir …’ he began, and the words seemed to tremble a little. ‘You will forgive me for this untimely intrusion. Had it been possible, I would have deferred my visit until tomorrow, and to a more suitable hour. But, alas, duty dictates that I should lay this matter before you with the greatest urgency. Not a moment is to be lost. The situation I have discovered is … It is simply … Well, I can assure you, Mr Holmes, that if something is not done, and done quickly, my homeland faces utter humiliation and abject ruin, with consequences that will be felt – and deeply felt – from Vienna to St Petersburg, and even on these very shores.’

He paused as if for breath, and I heard Mr Holmes give that little click of his tongue that always betrayed his impatience.

‘Perhaps, General, you would be good enough to confirm for us precisely which homeland you refer to? Your card refers to the House of Capricorn, which I believe still rules over the Grand Duchy of Rosenau, but I confess your uniform confounds my knowledge of middle European military attire. I can tell only that you have travelled here today by way of Paris, where you first got wind of certain information. That information caused you to abandon an official engagement that had long been in your diary in order to travel to London with the greatest dispatch. Upon arrival here, you hastened to your consulate, where you were able to obtain further information – information that alarmed you so greatly that you felt obliged to call here without delay.’

Mr Holmes paused for the briefest of moments, as if to order his thoughts.

‘As for the cause of your perturbation, I can only speculate. But as the newspapers here are devoting an irresponsible amount of space to the forthcoming nuptials of the Rosenau heir, and as his marriage is considered vital to the future stability of the Grand Duchy, I assume that some obstacle has been discovered that might prevent the much-anticipated wedding from taking place. Am I right?’

It was, of course, not the first time I had known Mr Sherlock Holmes greet a visitor in such a way, but I confess that it still gave me a little thrill to hear it. Certainly, the effect of this speech on General Pellinsky did not disappoint, for that gentleman simply gaped for a full five seconds, then wiped his brow with a braided cuff and cleared his throat rather noisily.

‘I cannot begin to fathom how you have divined so much from my presence here tonight, Mr Holmes, but you are absolutely correct in almost every particular. You are, however, wrong in one crucial detail. No obstacle to the forthcoming nuptials has been discovered. It is still the will of the Archduke, and the expectation of the people, that the wedding should take place. Indeed, a great deal depends upon it. And if you have read the newspapers today, you will know that the date has been brought forward at the insistence of the Archduke himself, to precisely ten days’ time.’

‘We have read that, haven’t we, Holmes?’ Dr Watson confirmed sagely, his empty glass cradled gently in his hand. ‘Seems to be a great deal of excitement about it. You know, handsome foreign nobleman, beautiful foreign princess and all that. Childhood sweethearts, feuding factions united, and all of it taking place at a secret venue somewhere in the Home Counties. Just the sort of thing to appeal to the British public! But tell me, General, if no obstacle has arisen to prevent true love running its course, then what brings you here tonight?’

‘That, sir, is what I am about to explain.’

The visitor took a deep breath and cleared his throat for a second time.

‘You see, Doctor,’ he went on, and even from where I was standing I could see his pale cheeks flush as he spoke. ‘You see, Doctor, it appears we’ve managed to mislay the bridegroom.’

At that hour of the night, the street outside was quiet, with few pedestrians and little traffic. In the brief silence that followed General Pellinsky’s dramatic utterance, I could hear the hoof-falls of a single dray horse plodding beneath the study window.

The silence in the room was broken by the sound of Mr Holmes rapping his pipe sharply against the mantelpiece, an action that I believe betrayed a degree of interest, since I knew for certain that his pipe was already quite clean of tobacco. The sound seemed to rouse Dr Watson, who rose from his armchair and stepped to the drinks tray, refilling the general’s glass as well as his own. It was as if the bald statement of our visitor’s problem had in some way broken the tension, and when Mr Holmes spoke, he sounded completely at ease.

‘Perhaps, General, if you were to tell your story from the beginning. The Grand Duchy of Rosenau is, I believe, one of those semi-independent states that have survived in various parts of the Balkans despite the recent upheavals?’

‘That is correct, sir.’

The...