"You clearly know something of irksome labour, Doctor," my patient began once the others had departed, with a great many coughing fits and pauses for breath which I will not include here. "But I doubt you have ever been so brain-weary and footsore as I... Bah! Sometimes I feel inclined to throw the whole thing over – name, wealth, position – and take to some modest trade. But I know if I abandoned my ambition – hardly as she uses me – I should have nothing but remorse left for the rest of my days."

I looked at him in astonishment. If ever I saw a man in the depths of poverty, it was the man in front of me! His burns notwithstanding, there was no mistaking the frayed and unkempt state of him before the explosion. And he was talking to me of the irksome worries of a large business? In other circumstances, I might have laughed outright. Either the poor man was mad, or making a sorry jest of his own misfortune.

"Yes, well, high ambition does have its compensations..." was my feeble reply, but I regretted the words the moment I uttered them, as my patient gave me a dignified look that utterly transcended his haggard features.

"I forgot myself. Of course you don't understand. In spite of all my troubles, I really have a big business in hand, a very big business. The fact is... I make diamonds." Something in my expression must have betrayed me, for he gave a rasping sigh. "I am sick of being disbelieved!" Reaching inside his ragged coat, he pulled out a little canvas bag that was hanging by a cord around his neck. From this he produced a rough, dark pebble and handed it to me. "I wonder if you know enough to know what that is?"

And indeed, the years I had spent as Holmes's friend and colleague had given me a smattering of mineralogy, in addition to my university studies. The stone was not unlike a raw, uncut diamond, but much too dark, putting me in mind of Moissan's first abortive efforts with his electric arc furnace. Saying as much caused my patient to nod impatiently.

"Diamonds," he began – and as he spoke, his voice assumed something of the easy tone of an educated man – "are made by throwing carbon out of combination in a suitable flux and under a suitable pressure; but no one has yet hit upon exactly the right flux to melt the carbon, or exactly the right pressure to crystallise it. Thus the diamonds made by chemists are small and dark, worthless as jewels. Now, I have given up my life to this problem – given my life to it! I was seventeen when I began..." He laughed hoarsely. "Tell me, Doctor, would you have guessed me to be but thirty-two? It seemed to me that it might take all of a man's thought and energies for ten, twenty years, but even if it did, the game was still worth the candle. Suppose one at last just hit the right trick before the secret got out, and diamonds became as common as coal? One might realise millions. Millions!"

He paused and looked for my sympathy, eyes shining hungrily. "To think," he said, "that I might be on the verge of it all, and yet shut away here!

"By great good fortune, I had inherited a thousand pounds when I was twenty-one, and this, I thought, eked out by a little teaching, would keep my researches going. A year or two was spent in study, at Berlin chiefly, and then I continued on my own account. At first I had a little laboratory, but as my resources began to run out I had to conduct my experiments in a wretched unfurnished room in Lambeth, where I slept at last on a straw mattress on the floor among all my apparatus. The money simply flowed away. I grudged myself everything except scientific appliances. I tried to keep things going by a little teaching, but I am not a very good teacher, and I have no university degree, nor very much education except in chemistry, and I found I had to give a lot of time and labour for precious little money. But I got nearer and nearer the thing. And now, I believe I have discovered the correct composition of the flux!"

I was by this point convinced that my patient was indeed a fellow student of science; jargon aside, his eyes were alight with all of the fervour I had seen in Holmes's whilst conducting an experiment of his own devising... and a fair few of those had ended in much the same fashion! "I gather, then, that discovering the correct pressure remains a work in progress?"

"Yes. This evening, I put the flux and carbon into a closed-up gun barrel, filled it with water, sealed it tightly and heated it."

I resisted the urge to sigh. "And did you not think that might be rather hazardous?"

"It was in the interest of science," he said dismissively. "Alas, the barrel burst, and smashed all of my windows and most of my apparatus. I shall have to try a cylinder with a screw cap next. Daubrée, you see, tried exploding dynamite..."

I had now heard enough, and raised my hand to stem his diatribe. "My dear sir, I... I hardly know what to make of all you've told me." For my part, I more than half believed his story... yet had not Holmes pointed out for years that credulity was one of my besetting sins? "But in any case, you surely cannot think that any officer of the law would allow you to continue performing such volatile experiments! Why, you might blow up the entire building next, or kill someone else!"

"Will you not aid me, then?" he cried. "You know I am no anarchist, you could assure your policeman friend I meant no harm..."

I shook my head regretfully. "Inspector Lestrade is not the man you would need to convince, my poor friend." Even if he were, and I could have afforded bail, my patient could hardly return to work in his former laboratory, or in his present state of health! "You forget, the report I am duty-bound to write will end up on higher desks than his. The very least of your unwitting offences is criminal negligence, and you will be made to stand trial for it. However," I hastened to add as his eyes screwed shut in despair, "I can ensure that whatever remains of your work is kept secure while the courts determine your fate. Lestrade will tolerate no thefts or tampering with evidence, I promise you." I smiled and gently patted his bandaged hand while he eyed me doubtfully. "Whether it be days, weeks, or months from now, your property will be restored to you the very hour you are set at liberty, and you may continue your quest. I shall wish you all the luck in the world."

~0~

And who could tell, I mused as I left the cell, having done what little I could to give him a comfortable night; a decent period of enforced rest for the poor man might well provide food for thought as much as physical restoration. How many times had I seen Holmes do the same: step back from a problem to seek a fresh perspective, which so often turned out to be the correct one!

If only I could have found a little of that same inspiration. Lestrade grinned in sympathy when he found me staring at a mostly blank sheet of paper.

"Need some help?"

I nodded gratefully, and he pulled up a chair. "My apologies to you and all our colleagues, Lestrade. Writing up my own case notes had nothing on this!"

He chuckled. "Had quite the tale, did he?"

"You might say that..."

"Well, what about this: you repeat what he said to me, and I'll translate onto paper as we go."

"Well, that's... very kind of you..." Lestrade was certainly far more practised in the appropriate phrasing for a report of this type... but now that I actually came to tell someone else my patient's story, all of my earlier doubts were creeping back. I also knew well how such a narrative would sound to a more pragmatic ear than mine – Lestrade would most likely laugh himself into stitches at the very idea of making diamonds, and in such a makeshift laboratory! Then, too, from a purely ethical standpoint, was it right to reveal the nature of my new friend's experiments to anyone, before he had even been granted the chance to perfect and patent his methods?

"Actually, Lestrade... I think I'll muddle through on my own this time – thanks all the same." I gave his raised brows a strained smile. "Oh! One thing before you go, though: the prisoner was very anxious about his scientific apparatus. I told him I'd ask about whether it might eventually be returned to him."

"What's left of it, I hope he means!" Lestrade snorted as he stood up again. "Well, I really don't know – it'll depend largely on the verdict, of course."

"I know, but... did anybody at the scene happen to find a large metal tube, burst open at one end?"

Lestrade gave me a Look. "Before they dragged our battered friend out by the light of flaming wreckage, or after?"

"Right, sorry," I mumbled, face growing warm. "It's just that he claimed the materials he was working with in that tube were rather valuable, and I had to promise him we'd find it to keep him calm..."

"All right, Doctor!" Lestrade sighed. "I'll drop in at the fire station first thing tomorrow, will that do?"

"I suppose so... Yes, thank you, Lestrade," I amended hastily, appalled at my unthinking rudeness – I must have been more tired than I'd thought! "That would be most helpful." Nothing else could be done until the morning, anyhow... except for finishing this blasted report.

~0~

"Mary?" I called softly as I closed our front door behind me. No reply came – not that I had really expected one at this time of night, Mary must have gone to bed hours ago. I hung up my hat and coat, exchanged my damp shoes for a pair of slippers, and shuffled slowly to the kitchen in search of a late supper.

To my surprise, Mary sat dozing in a chair beside the stove, mouth open, the book she'd apparently been reading perched precariously on her knee. I rescued it as delicately as I could, but the movement was enough to rouse my wife, blinking up at me blearily. "...John?"

"I'm sorry, Mary," I murmured, and bent to kiss her. "You shouldn't have waited up so late."

Mary gasped as our lips touched. "Ooh, John, you're frozen!" She stood and pushed me down into her chair. "You sit right there and get warm, I'll make some tea."

I nodded gratefully, too tired to argue. "How was your day, love? Did anything interesting happen?"

"Mm, only if you count Wendy Albright's sister, do you remember Wendy? Long black curls, hosts our ladies' sewing circle on Thursdays? Anyhow, her sister had turned up unexpectedly for a visit from Hertfordshire..."

I leaned back in my chair with a sigh, letting Mary's voice and the sound of tea-making wash over me. In this warm, homely space, the chill of the prison cell and its occupant's hypnotic tale suddenly seemed very far away...

"John?" Mary's hand on my shoulder made me startle, her brows knitted in concern. "Darling, are you all right? You were muttering in your sleep!"

"Oh... No, no, I'm fine, honestly," I smiled, accepting the cup she held out. "I just had a bit of an unusual patient at the Yard before coming home, that's all. Stupid fellow..." I silently begged my friend's pardon for such a casual dismissal of his magnum opus. "He'd half destroyed his lodgings messing about with explosives!"

"Oh my goodness! Well, what a mercy you were still at work! Was he badly hurt?"

"I'm afraid so. Which reminds me..." I eyed Mary sheepishly. "Sweetheart, I know I promised to take the whole day off tomorrow, but..."

"But you want to see to your new patient first," Mary smiled, with only a hint of a resignation in her voice. "Of course you must go."

"It shouldn't take long," I assured her. "Half an hour, then the rest of the day will be ours."

"It had better be." Mary wagged a roguish finger at me. "You've been home so little lately, if you aren't careful I might start to think myself an old maid again!"

"Glad to hear it," I murmured, reaching out and drawing her close. "Then I could court the sweetest woman in the world all over again, win her heart even faster the second time."

Mary laughed, blushing, and rewarded my barefaced flattery with a tender kiss.