This story was inspired to me by watching the Sherlock Holmes movie with Robert Downey Jr. Nevertheless, it's not set in the movies' universe, but in the literary one. It's meant to be a crossover between Sir Arthur Conan Doyle's version of Holmes and the Harry Potter universe as I imagine it to be in the late 19th century. I hope you enjoy it!

As an added curiosity: in order to pick plausible addresses in Victorian London for the characters here mentioned I referenced Charles Booth's poverty maps of London, as found here: . /map/14/-0.1428/51.5323/100/0. Probably a very useful tool for anyone wanting to write fiction set in that time frame!

The strange case of the emerald necklace

During the years I have recounted a great number of the cases in which my dear friend, Mr. Sherlock Holmes, was involved, often with some modest contribution by yours truly. As it must happen to anyone dealing with that product of the most sordid, animal passions of human beings, and of the most twisted applications of their intellect, that is, crime, we have seen our fair share of horrors during those adventures. None, however, can be said to have ever been as terrifying to us as the one I am about to tell you; and none opened our eyes to a deeper abyss of dark possibilities. I am a man of science, yet my hand trembles, and my mind rejects the facts it has been witness to, when recounting this tale. I commit it now to paper so that it may not be entirely forgotten. I am sworn to secrecy, and this manuscript will never see the light of a publication. But perhaps one may find it, in the future, long after I'm dead and my soul is either safe or damned forever. To them I will leave the choice to either believe or not my tale, and if they do, what to do with the knowledge.

It was a rather lovely autumn afternoon when a distressed woman looking for Holmes came to knock at the door of our Baker Street apartment, as it often happened. We showed her to the living room and let her sit down, then Mrs. Hudson brought some tea and biscuits to help put her at ease. She was a pretty little thing, but clearly her nerves were wracked by some great worry. Her eyes kept darting about, like a doe's looking out for the wolf that's stalking her. Her hands were also unsteady, and she would often fidget with her own fingers or with the jewel dangling from her neck - a small, shining emerald which I imagined must have had quite some value, with a thin silver snake coiling around it.

My friend Holmes must have sniffed already the trail of an interesting and peculiar case (little did we know how peculiar, yet!), because he immediately jumped to the point.

"I can see already from your appearance that you must be in desperate need of help," he said. "Your life is obviously in danger, and I hardly think you coming here is unrelated to that fact. Therefore, let us discuss the details of your case, miss...?"

"Cooper," she replied, sipping from a cup of tea, but still slightly on guard. "My name is Artemisia Cooper. And you are right about my life being in danger. How did you guess?"

"My dear! That is hardly the subject of doubt," said Holmes, scoffing. "I can tell at first glance that you probably work as a maid; that you are unmarried; and that you have a darling that loves you very much but is socially above your own station, just from observing your attire. But that you fear for your life, why, that is simply written all over you. I am sure my friend Dr. Watson, who is only beginning his training in the science of deduction, can't have missed that either."

I quietly nodded at that, and miss Cooper smiled faintly. "Right on all counts, Mr. Holmes. You truly are as clever as they say. This gives me, perhaps, some hope. But may I ask you how did you infer all that?"

"Quite simple, really, if one knows where to look," started my friend. "Your clothes are cheap, but show a cleanliness and professionalism in the way they're ironed that betrays great experience. You are not rich, but you look like you have a maid keeping care of your things: hence, a maid yourself. You have no rings at your fingers, so you are not engaged or married. Yet you keep at your neck a very beautiful emerald necklace, which seems far above your means. So, I imagine, a gift, from a suitor whose wealth must be almost equal to the affection he feels for you."

To this, the woman blushed slightly and clutched the necklace with her right hand, hiding it from our view, perhaps in a gesture of shyness. But in her eyes I almost thought I saw a glint of satisfaction, instead. "And is there anything else you can tell without me saying?," she asked.

"I get the feel she's trying to get a free show out of this," joked Holmes, looking at me. "But yes, there is. I said that you look very much in danger, but I also imagine that danger is more than speculation. On the tips of your fingers I can see some residue of ink, of the sort that Scotland Yard uses to collect fingerprints. Since I would hardly imagine that you were a suspect, I deduce you recently denounced a crime, and your fingerprints were taken to separate them from those of the culprit when examining the scene."

Miss Cooper lowered her eyes. "On this, I am afraid I must tell you you're only half right," she said, under her breath. "It is true that I have denounced a crime, and that I have been to Scotland Yard this very morning. But I also am a suspect. Mr. Holmes, yesterday night I was attacked in my home, and in self defence, I killed a man."

At this, Holmes leaned instantly in, his interest obviously flaring up. As for me, I could only feel a pang of pity for the poor girl. As war had taught me, killing is never a simple matter, even when done to protect one's life. That such a young woman should be subject to the knowledge of having done so horrible a thing seemed too painful to me to contemplate.

"From now on, I trust your discretion," continued the woman, and Holmes merely nodded along. "for what I am about to talk involves many sensitive matters that should not be discussed at large and may ruin many a reputation, and endanger more than a life. As you so aptly deduced, I have a fiancée. The engagement is a secret, but that is not out of any wish of ours."

"Rather," jumped in my friend, hasty, "his family is opposed to it."

Miss Cooper nodded. "I can not reveal the identity of my fiancée, or his family. It is too sensitive a matter, and I would not like you to get tangled with them, for your own safety. Suffice to say, the situation is so unbearable, we have decided to elope to America."

"But what does this have to do with the risk to your life?" I asked, and immediately gasped in horror as I realised. "Sure you don't mean-"

"Yes, Dr. Watson," said the woman, with a bitter smile. "We believe my fiancée's family is trying to have me killed, so that they may bring their dear son back into their warm embrace."

"But that is awful!" I shouted. "I have heard of many noble families who would frown at the idea of their scion marrying a commoner, but none to such a fanatical extent!"

"Well, I suppose we might have just heard of one," said Holmes, brusquely. "Please continue, Miss."

"With pleasure - if of pleasure one can speak, recalling of such dreadful events. My fiancée warned me that something like this might happen a few days ago. He was mad with worry, but knew he could not be by my side to protect me at all times, and there were certain financial arrangements that he needed to take care of before we could just leave the country. He left me instructions on how to stay safe at all times, and a small gun, of the sort that can be concealed on your body. Yesterday night I heard some noise coming from the front door of my house. My sleep, you see, is very light. I grabbed the gun and carefully approached the entrance. Someone had broken in. The front door was open, and there was a case full of metal tools on the side. The man himself was big, with thick arms, and a knife in one hand. I was terrified, but I managed not to shout. I stepped into the light. When he saw me he had one moment of surprise and raised his knife, but at that point I had no longer any doubt what he had come to do. I shot him in the gut."

I almost winced at that. I was not sure even some of the soldiers that I had fought in Afghanistan with would have demonstrated the same cold blood and resolution that this woman seemed to possess.

"The rest is more or less as you guessed it," continued Miss Cooper. "I have denounced the break-in to Scotland Yard, and recounted how I had defended myself. The inquiry is still ongoing, but I expect to be cleared - everyone seemed very sympathetic, and Inspector Lestrade agreed that it was obviously a case of legitimate self defence. But I still fear for my life. Due to the circumstances that I described, I could not disclose to the police the reasons for the attack, and therefore could not ask for their protection. If I were to be attacked again, this time, they may succeed."

Holmes frowned. "So you are looking for a bodyguard?"

"Of sorts." agreed the woman. "They won't dare attacking me during the day. I only need protection for a couple of nights before we can leave for the United States. But I would much appreciate your wit and investigative prowess too, Mr. Holmes. My fiancée suggested that if something else were to happen, having evidence on whoever hired the thugs would allows us some more breathing space."

"You mean you want information to blackmail your fiancée's family?" I asked, bluntly.

"I only wish to have means to protect myself," she replied. "I do not plan to leverage them for anything more than my and my fiancée's own life and freedom."

"You do not have any such evidence yet, though," pointed out Holmes. "It could well be that your assailant was a mere common thief, and the whole affair just a coincidence."

"If that was the case, Mr. Holmes, then this will be an easy job indeed for you. I have the money to pay you, provided by my fiancée, of course."

I was rather stunned by the directness and frankness with which the request had been laid upon us. Even more surprising to me was the terrible determination that I could glimpse within the woman's eyes. I thought whoever it was that she loved, he must be worthy of envy for it. Here was someone who was clearly ready to go through Hell and back for him, who had just gone through a horrible ordeal and yet managed to keep herself composed, and even planning for the future through all of it. Yet, her nerves weren't as steely as she made such a grand display of. I could see her occasionally shaking, or tensing up at a noise from the street. Her hands kept going back to the emerald necklace, too. She would grasp it, as if to protect it from our eyes, or occasionally caress it with her index finger. It had a weird, magnetic allure on me, which kept drawing my stare to it time and time again.

All through this, I fully expected Holmes to refuse the case; after all, it seemed trivial enough, if with some scandalous implications, and guarding people was not his occupation of choice. But to my surprise, instead, he thought for a long while, puffing a bit in his pipe, then leaped up to his feet and "I'll take the case!" he exclaimed, stretching his long arm to shake the woman's hand.

She offered many thanks for that, and promised eternal gratitude. After some more niceties, she paid up a substantial advance, greeted us and Mrs. Hudson one last time, and gave us a card with the address at which she wished Holmes to meet her that very evening. It was an address from a rather unremarkable neighbourhood in the part of London south of the Thames.

"13 Weston Street," mumbled Holmes, turning the card in between his fingers with a thoughtful demeanour.

"It surprised me that you accepted this case," I remarked. "What is it that you expect to find in it to tickle your interest?"

"I do not know," he said. "That's what intrigues me."

On that night, I did not accompany Holmes on his task. I had a previous engagement, meeting a couple of old friends for dinner and then a game of cards, and discretion suggested that it would probably be better to have him deal with the matter on his own. I knew my friend for an excellent marksman and pugilist, and so did not worry much for his safety. Any thug who showed up to attack a single defenceless woman would be in for a surprise. The dinner was over, and we were merrily playing a round of whist while sipping some excellent liquor one of my friends had brought, when the postman knocked to my door. I was worried and surprised, and seeing that the note was from Holmes only exacerbated those feelings. I opened it up and felt the blood leave my face.

Miss Cooper dead. Please come find me now. 5 Archer Street, Camden Town. Make haste.

My friend had failed! That he had sent me a note at least meant he was still alive and in good health, but that puzzled me even more. That he would let an ordinary criminal slip under his watch and murder a client seemed to me almost as outrageous a conceit as him getting killed by one. More so, I did not recognize the address. But giving this little thought, I called the first cab that I could find crossing the street, handed a shilling to the cabby and gave him the address, telling him to be as quick as he could. Being night, the roads were quite empty, so we arrived soon after. I got down and saw that the police was already all over the house. There were two cops waiting outside, and when I tried to enter, I had to make explicit mention that I was a close friend of Mr. Holmes to let them pass. The house itself was modest, but well kept. And as I entered the bedroom, I saw the grim spectacle. On the linen bedsheet drenched in blood lay Artemisia Cooper, Holmes' client, dead. A gunshot wound had pierced her chest, and at a glance, life must have left her not long ago, for her body was still not even stiff.

Next to the bed were the coroner, a much worried Inspector Lestrade, and Sherlock Holmes.

"Holmes!," I shouted at him. "What has happened here?"

"Watson, finally!," he replied. "As the most basic powers of deduction are likely to tell you already, a murder. But beyond that, I am still as puzzled as you are."

"But how?," I asked. "Miss Cooper had asked for your protection. And I am sure the address was not this one. It was at the very other end of the city!"

Holmes smiled. "You would be, wouldn't you? So was I. But prodigiously, it seems we both were wrong."

And saying so, he handed to me a card he took from one of his pockets. I could clearly recognise it as the same from this morning - same colour, feel at the touch, handwriting even - but the address now read, without mistake, 5 Archer Street.

"What does this mean?," I stuttered, in genuine confusion. I was confident enough in my own memory, but to think that Holmes' could have failed on something so trivial was downright unbelievable. "Was the card forged?"

"Alas, it's the very same," said Holmes. "I even marked it this morning - just a little habit I have - left a small dent in the side with my fingernail. It's still there. It was not swapped or replaced, and clearly not erased and rewritten by any means, or it would have left a trace."

I was bewildered. "What then? Did we both just remember it wrong?"

"Apparently so, Watson," he replied, thoughtful. "But that is the least of it. Around six in the evening I took a cab and had it lead me to the wrong address that we both were so sure we had seen. I arrived at quarter past six, at most. The door of the house was open, but it seemed empty to me. I waited for what I thought was just ten minutes, and then re-checked the card. Imagine my surprise when I realised the address was completely different! I rushed out and managed to arrive here as soon as I could. It was half an hour at most. Yet when I arrived, it was too late. The house had been broken into, and I found Miss Cooper laying down as you see her, on the bed, her emerald necklace still around her neck."

I quickly ran the numbers in my head. "That can't be!," I exclaimed, finally. "It is past midnight now. Surely, if so much time had passed, rigor mortis would have set in already..."

"Your medical knowledge is spot on, of course, Watson," reassured me Holmes. His gaze betrayed that he was deeply lost in some maze of thought. "It was me who lost track of time. What I thought had been ten minutes in the house on Weston Street was, apparently, almost three hours. Three hours of which I don't have the faintest memory."

To this, I did not know what to say. I felt a terrible dread for my friend - perhaps his mind was falling victim to some kind of dementia, an illness that would cause his memory and intellect to fail? It is rare in the young, but not unheard of, after all. But no, I, too, had been a victim of an inexplicable trick of my memory, with the address card. Something different was at play here, something that begun to feel downright sinister, even if it did not involve the murder of a young woman.

"What is going on?," I managed to stutter.

"It will be interesting finding out, won't it?," said Holmes. "And there is another piece of the puzzle that I believe is essential to solving it. Surely, you must have noticed."

I must admit, I had not. But just taking a longer look at the crime scene, and the lifeless body at its centre, made me realise.

"The emerald necklace is gone."

"Right on the money, Watson. But as I told you, I am fairly certain that I did see it when I found Miss Cooper's body."

"But what could it mean?," I said, confused. "No one could have stolen it with you and then the police here in the room! Another trick played by your memory?"

"I still think you're just wrong, Holmes," intervened Lestrade. "It happens to the best. A thief broke in, killed the woman, and grabbed the most valuable thing they could find. Then you simply got your memories mixed up after showing up here."

"Perhaps. And perhaps not." replied Holmes. Then, already lost in thought, he grabbed his coat, swung it around his shoulders, and stormed out of the room. I followed suit.

The next day was a rather dreary affair. I woke up early, still haunted by the image of the dead woman from the night before. It surprised me as, horrifying as it may be, death was not unfamiliar to me or my profession altogether. Yet this one image seemed to have struck a chord within me, and had been coming back again and again in my dreams that night. Sometimes she would already be pale and lifeless, and I was the one discovering her in place of my friend Holmes. Sometimes she would still be alive, afraid, running from her murderer, which disturbingly was myself. And sometimes I would come close to examine her body only to see her open her eyes and look straight into my own, with a piercing stare that seemed to come from the depths of Hell.

But for all that, when I finally trudged out of my bed, more exhausted than when I had gotten in it, I found Holmes already awake and in an awful mood. He was buried into one of the living room's armchairs, puffing in his pipe, frowning and thinking. Whatever amazing machinery animates his incredible mind, you would have thought you could hear it ticking and clicking in vain, as it failed to reach an answer to the many questions it was confronted with.

"Good morning, Holmes," I mumbled.

"Morning?," he replied. Then he checked the clock, and finally seemed to notice the light outside. "Oh, right. It has been a while I guess."

"As a doctor, I can't agree with you treating yourself with such disregard, you know."

"And as a fellow human?"

"Wish I could have done the same," I grumbled, rubbing my forehead and slumping into the couch. "It's not like sleep helped much. Is there going to be coffee?"

"Mrs. Hudson is preparing it now, I believe," said Holmes, and then added nothing more, signalling that the conversation was over. I didn't mind; I wasn't in a mood for chatting myself. Soon, Mrs. Hudson showed up with a tray with a few cups, a coffee pot, and biscuits, plus the morning newspaper. I hoped that finally breakfast could help me find some relief from both my troubled mind and my piercing headache, though I wasn't very optimistic about either. As she laid down everything on the table, I could see Mrs. Hudson too seemed strained. Under her eyes were deep bags, and she winced in pain when bending over with the tray.

"Is something the matter?," I asked her.

She shook her head. "A bad night," she replied. "You fellows should quit talking about murder and crime every day. You're beginning to affect me. I dreamed of that poor girl you mentioned yesterday evening all night. The poor thing!"

This coincidence should have perhaps surprised me more, but I was already in a foul mood over it, and it did not strike me as strange that someone else might be too. I just poured myself some coffee and drank it, awash in rather dark thoughts.

I picked up the newspaper and that only made my mood worse. The murder of Miss Cooper was indeed reported, and described in most lurid detail to boot. Worse, a mention was made that Sherlock Holmes had been the one to find the body, and that he had 'failed his duty as hired bodyguard' to the victim. Luckily, that was as far as the details went - a mention of the great Sherlock Holmes showing up at the wrong address would have been a coup de grace for his whole career. I did not read any of that to my friend, though. He seemed preoccupied enough as it was.

"Mr. Holmes, your coat is dirty." said Mrs. Hudson, scandalised. She examined the thing, hanging near the door. It was indeed in quite the sorry state, after all the scurrying around he had done yesterday in the muddy streets.

"I suppose it is," replied Holmes, annoyed.

"May I wash it for you, then?," continued the woman, undeterred. "Don't worry, I will empty the pockets of any-"

"NO!" shouted Holmes, suddenly rising from his chair and jumping forward.

I raised my eyes, shocked. The man was clutching Mrs. Hudson's wrist with such a violence she was actually in pain. All the woman could do was look at him transfixed and scared from a behaviour that had absolutely no precedent.

"Holmes, what are you doing?," I asked, walking to him. "Why can't she empty the pockets of your coat?"

Holmes thought about it for a second. He seemed genuinely puzzled. He let go Mrs. Hudson's wrist, and she started to massage it. Holmes' own expression shifted from confusion to a jolt of anger to a spark of understanding.

"I don't know!," he finally said, and his face brightened up.

At that point, I was all but sure that he was simply going mad. "Holmes, what in bloody Hell are you talking about?," I shouted. "You don't know? And you're happy about it?"

"I don't have the faintest idea!," he insisted, and he grabbed my shoulders and shook me, absolutely jubilant. "Oh, don't you see, Watson? This makes sense, finally! I can't let her rummage through my pockets, but I don't know why! Oh, this makes so much sense now. Eliminate the impossible, and what remains... I could not imagine. But then I need to think about... quick! A diary!"

He darted to the other side of the room, grabbed a daily planner book from a desk and started shuffling the pages furiously.

"Tomorrow, or the day after. I must check-"

"Holmes!," I said, grabbing him myself this time. "Can you tell me what this is about? What have you realised? Have you solved the case?"

"Not yet," he replied. "But soon. Oh, but I will need your help. I'll let you know the date and time. Now, if you excuse me, I need to go to my room and find out."

"Find out? Find out what?"

"Find out what else is it that I can't do," he said, as if it was the sanest answer in the world rather than the rambling of a madman. "Now leave me some time to think. And leave that coat alone!"

And to make sure his order would be followed he ran back to grab it from the hanger, then dashed into his bedroom, slamming the door behind himself.

For a whole day I didn't hear or see any news from Holmes. Had anyone else locked themselves in a single room for so long I would have been mightily worried for them - but this being him, it was usual fare, and I did not pay him much more mind. The next night was as troubled to me as the one before, and for Mrs. Hudson too, I learned. I then started wondering whether something sinister was at work, and what curious suggestion might compel such similar visions in both of us. Talking it out with our landlady I had also discovered even more worrying details, such that she could describe the appearance of Miss Cooper's dead body with unsettling precision for one who had never been on the crime scene to begin with. Had I been not sceptical to a fault, even that fact alone might have alerted me that what we were dealing with veered off from the simply criminal, and straight into a far darker territory.

Finally, I got the contact Holmes had promised. Most unusually, he saw it fit to leave it to me in the form of a sketched note dropped on my desk in my absence. I read it, and was more confused than before.

Come to St. Paul, near Bermondsey Market, tomorrow at 9 in the morning. Wait until you see me walk past, then follow me as discreetly as possible. Join me when I reach my destination.

For all of Holmes' occasional quirkiness, this went above and beyond. I was so at loss, all I could do was follow the instructions to the letter, if only to find out what was his ultimate purpose, or if he had really gone off the deep end. The morning after I was out and about quite early. I had to cancel some appointments at the clinic where I worked at the time and it was a damn cold morning to be waiting in the street to boot, so I hoped when Holmes finally showed up some long overdue explanation would be in order. Granted, he did appear, eventually, but he ignored me entirely. I could only suppose he suspected he was being followed himself, and did not want to clue his pursuer on my presence. I checked the heavy, reassuring metal of my revolver I kept in a coat's pocket and set out to follow him, discreetly, as he had requested. It was not a long walk. Soon after, he came to a stop in front of the door of a rather dilapidated house that seemed to have been uninhabited for quite a while.

The address was 13 Weston Street, the same we both were sure Miss Cooper had given us on the day we saw her alive.

It was out of the question that this could be just a coincidence. I snuck closer to the house and glanced inside. The room was dark, but my eyes could discern the tall, imposing figure of a man besides Holmes. His blonde air caught a few glimpses of whatever little light reached him, and he seemed to be clothed unusually, in some kind of long robe. A priest, I thought at first, but then saw trimmings and decorations that were far too rich and fine for a member of the clergy any lesser than a bishop. No, his garments did not seem priestly at all, on closer inspection. If anything, they had something that reminded me of the freemasons, or what I knew of them. The man beckoned at Holmes; in his right hand he kept something that looked like a thin stick, similar to that an orchestra's conductor would use. Holmes slowly walked to him, as if in a trance, and put a hand in a pocket of his coat. Then out of it he pulled something. Imagine my surprise when I realised it was the emerald necklace that had disappeared from the crime scene! My only conclusion could be that this was one of the criminals behind Mrs. Cooper's murder, and that he had been somehow blackmailing Holmes into procuring him the necklace. I could not understand the details, but at the time, they did not matter. I slammed the door open, my revolver pointed forward.

"Drop everything, hold your hands high, and step away from Sherlock Holmes!," I shouted, trying to make it as clear as possible that I was not bluffing.

The man, however, was not fazed. He lightly flicked the stick he kept in his hand and whispered a word in what sounded like Latin. A bolt of light darted out of it and hit me, and the revolver escaped my hands, falling on the floor. I was still looking at my hands, unsure of what had happened, when there was a flash of action. The criminal's eyes were on me, and thus he did not notice Holmes suddenly stepping closer, grabbing his right wrist with one hand, and with the other pulling out his own gun, which he pushed straight below the man's chin. The man seemed surprised, then alarmed; but finally burst in a fit of laughter, in spite of the weapon that was only one trigger pull away from blowing his brains out.

"Oh, Mr. Holmes!," he said, raising his other hand in sign of surrender. "You truly are as extraordinary as they say. To think that a muggle, of all people, could resist my orders."

"I do not know what a muggle is," said Holmes "but I must confess you are perhaps overestimating me. I could not, in fact, resist your orders. I merely acted around them. I admit, your hypnotism is so amazing, I would not have believed it possible had I not felt the effects myself."

The criminal smirked. "Hypnotism? I'm afraid not, Holmes. That is just the most imperfect muggle version of an art we have refined for centuries. By muggle I mean, you understand, any of you people who do not possess magic."

"He's a madman!," I said at that. "Holmes, let's just bring him to the closest police station."

But to my surprise, Holmes did not seem nearly as incredulous as me. "Magic, you say," he mumbled. "That would explain some things. But I could not - would not - believe such an extraordinary claim without evidence."

"You've seen what I've done to your friend's gun, Holmes," said the man. "But to demonstrate at my best, I need to be able to use my wand. If you would please release my arm-"

"Holmes, don't!" I shouted. It was irrational, I knew it. Did I really believe that this man could perform magic? That simply being able to wave some kind of wooden stick would give him power over us? And yet, at some level, I think I already did believe it. I felt like letting him use his wand, as he called it, would have been a terrible mistake.

"I swear I will not harm you or your friend, Holmes. I swear on what I have most dear at this world: on Artemisia's love."

"Have some decency, you monster!" I screamed at him, and I wished I could punch him until he stopped talking forever. "You killed that poor girl!"

His face darkened. "I did not kill her myself. But I did allow it to happen, true. And yet, my love for Artemisia is still as great as before."

"Dr. Watson makes an excellent argument, though," said Homes. "Why should I free you and take the risk?"

The stranger's voice got cold and sharp. "Let's do it this way, then. You should free me because I order you to."

I thought I was going mad. Sherlock Holmes, that most rational of men, that I would have thought completely impervious to suggestions and parlour tricks of any kind, followed that order. He lowered the gun and let go the man's wrist. He did so with seeming reluctance, but nonetheless, he did it, and took a step back. One moment later he seemed to snap out of whatever trance had overcome him and immediately lunged forward again, but this time it was too late. The stranger flicked his wand again.

"Crucio." he hissed.

And Holmes screamed. Overcome by pain, writhing, struggling, kicking on the floor, he screamed as inhumanly as I had ever heard anyone scream. I had amputated arms and legs to men without anaesthesia on a battlefield, and they had not screamed as much, or looked as much in pain, as Holmes did at the simple word of an unarmed man. One second later, it stopped, but I could never forget that I had seen and heard it. Pain like I didn't think could exist.

"I'm sorry if that was a bit excessive," said the man, with a smirk that suggested he was anything but, "Hopefully, that will clear your misconception that I am merely a very skilled hypnotist."

"Suggestion...," huffed Holmes, still wheezing and gasping for air. "Suggestion... is a powerful weapon. You already hypnotised me... so you could have left a command for... the emergencies. Not good enough..."

"Hm, stubborn to the end, I see. Let's try this," and he pointed the wand at me. I lunged at the gun on the floor, in horror, but did not make it in time. "Imperio!"

Every feeling of urgency left my mind. All tension relaxed. I felt at peace. The criminal looked at me, and I looked at him, expectant, waiting for his will, for the greatest joy of my life would be to just fulfil it.

"Do a cartwheel," he said, calmly, and with immense pleasure I took some run-up and launched myself in the acrobatic exercise as instructed. It had been a couple decades and one serious leg wound since my last time doing something like it, though, so it didn't exactly come off as well as it could have, and my back felt as if it was about to strain itself under the effort. That left me somewhat disappointed.

One second later I came to my own senses, was terrified at what I had just done and felt, and immediately grabbed the gun and pointed it at the man - at the wizard. He flicked his wand again with an annoyed expression and said, "Expelliarmus". My gun left my hands and again ended up on the floor.

"Or what about this?," he added, without even waiting for Holmes' reaction to these prodigies. He pointed his wand to a dark corner of the room, and only then I noticed there was dog. A stray dog, probably, as there are many on the streets, who had found refuge in the empty house, and was now sleeping quietly unaware of the drama around him. The stranger's lips opened.

"Avada kedavra," he whispered, and I felt a shiver in my bones, as if he had recited a forgotten, evil prayer to a pagan god. A green bolt of light emerged from the tip of the wand, flew through the room, and hit the dog.

"Go check it, doctor," he said, and I followed his instruction, stolidly, too stunned to do anything else, knowing already, instinctively, what I would find.

And I was right. May the Lord have mercy of us all, I was right.

"What did he die of, doctor?," asked me the man, bored.

"I can not say," I mumbled, defeated, turning around the poor carcass to look at it. "Not poison or anything visible. I would have to perform an autopsy to check for a heart attack."

"You could bring the body home and do it then, doctor," said the other, with a slightly sarcastic tinge to his voice. "I am sure it would be an instructive exercise. I can already tell you, you will find no plausible cause. That dog did not die of something - it simply died. I severed the thread of its life, snipped its vital force from its body, like Atropos of the Greek myths. Now, Mr. Sherlock Holmes, is that enough to convince you that I am telling the truth, magic does exist, and I wield this power?"

Holmes paused for a long time, seemingly lost in thought. Finally, "Yes," he said, "it is."

The wizard nodded and relaxed his wand arm, levelling it to the rest of his body. "Good," he said, finally. "Know that I do not mean to kill you. This I promised I would not do to Artemisia, and thus that is your guarantee. It was no simple promise either: I bound it with magic, to earn her full trust. I can not kill you without dying myself. I have not always been what you would consider a good man, Holmes. But I am trying to become one, for Artemisia's sake."

"A good man?," I repeated, incredulous. "You orchestrated the murder of the woman you say you love! You compelled Holmes into stealing a piece of jewellery from her corpse and bringing it to you! Is this your idea of love - of goodness?"

"Appearances can be deceptive, Dr. Watson," he replied, annoyed. "Any wizard with some wits to themselves learns that very early in their instruction. I will try to satisfy your curiosity. But first, I would like Mr. Holmes to satisfy mine. How did you realise what I had been doing, to the point of leading your friend here, and even taking me by surprise? A feat I must say I did not believe any muggle could possibly succeed at."

Holmes shook himself, raised from the floor, regaining his composure. Still, there was a weariness in his actions and words I had never seen before in him. He looked like a defeated man.

"When I realised the necklace was missing," he started, "my first thought was that the only person who could have removed it was myself. I did not remember doing it, but then again, my memory had already possibly been tampered with. I was considering a couple of options concerning the address on the card, racking my brain for any chemicals that could make one text disappear and another appear on a certain timing or a change of external conditions, but the necklace, that required someone to have done something to my mind."

"I was very uncomfortable at the thought, and yet I had to consider it. Hypnotism and mesmerism were things that I was aware of, though I had never heard of any form that was so powerful it could be used to commit a crime. The watershed moment was when Mrs. Hudson tried to grab my coat and search its pockets, and I felt an unreasonable compulsion to not allow her to do that. I immediately realised that must mean I had the necklace in it, and whoever had hypnotised me had ordered me to not let anyone else touch it."

The wizard nodded, visibly impressed. Holmes must have been spot on (and when was he not?).

"The rest was simply working backwards from that realisation," continued my friend. "Obviously, I had been lured to a fake address - this one - hypnotised, and given some orders. It was then a matter of realising what orders those were. I could not remember, but I was compelled to obey them none the same, and that meant I could realise what they were by examining what I could not do."

"If the culprit had forced me to steal the necklace, there could be only one other order left - to meet them, and deliver it. I then went methodically over the next few days, at every time of the day, and tried to put into my mind firmly the intention to do something at that specific time. It could be something as simple as going to the theatre or eating at a given restaurant. Thus, I found out this time and day, at which, for some reason, I felt like I just could not do anything. Because, of course, I was already committed."

"A similar reasoning allowed me to find the place. I worked backwards by restricting myself to commitments to go into various areas of London at that given time. Though I must say, it would have been far harder had you not made the oversight of setting our new appointment in the same place as our first meeting."

"Guilty as charged, Mr. Holmes!," laughed the wizard. "Do go on."

"I could not say to anyone about the meeting, but nothing forbid me to write. I could not bring anyone with me, but there was no issue with having them follow me on their own. And I was obligated to bring you the necklace, but nothing stopped me from doing what I wanted immediately after that. There, that is all," finished Holmes. "Do of that what you will. I believe that is a valuable lesson in weighing precisely your own words when giving orders to a man under your suggestion."

The criminal shook his head and slowly clapped, genuinely admired. "I must say, Mr. Holmes, that it is, and an incredibly humbling lesson at that. I wish my professor of Dark Arts had been as exhaustive, back in Hogwarts. But then again, I doubt he himself realised the power of loopholes in victims of the Imperius Curse. What you have achieved, Mr. Holmes, is something that even many wizards find very hard. We call it Occlumency. It is the mental discipline of redirecting one's own thoughts and memories and manipulating them in such a way to make tampering with them difficult, if not outright impossible, for an external force."

"A strict mental discipline is the tool of my trade," said Holmes, dryly.

"Indeed. Now, you put me in a difficult situation. I can not, nor would want to, kill you. I could try erasing your memories, but you are far too good at this for me to be sure that my poor Obliviation skills would be up to the task. If I left any holes, you would realise, investigate, and eventually we'd be back at this, which I would not want. Or you'd get yourself killed by snooping where you're not supposed to, and I do not want that either."

"So?," I asked, defiantly, however aware of how little my attitude was worth there and then. "What will you do?"

"I will do what honest men do to earn each other's trust," said the wizard. "I will tell you the truth, and confide that your discretion and desire to protect the life of an innocent woman will be the best seals to stamp on this mortal secret."

"The life of a woman?," I gasped, "Do you mean that Artemisia is-"

"Very much dead, I'm afraid," he continued. "But that is not all there is to it. I will explain. First, allow me to introduce myself. My name is Cornelius Malfoy, and I am a wizard. I am, in fact, the cadet son of an ancient noble family of wizards, who tracks its origins back to William the Conqueror's coming to Britain. As such, my kin are very strict about tradition, familial honour, and what we call purity of blood."

"I also am Artemisia's mysterious fiancée. I will not recount the details of our relationship - those are ours and ours only. Let us just say that her tale was entirely true. The only thing she left out was the real reason for why my family was so opposed to our engagement. Wizards of an old family like mine don't have a high opinion of muggles like you or her. In fact, they often consider them as lowly as animals. And have no qualms dealing with them as such if they feel like they're raising above their station."

"You mean murder," I muttered.

"Or worse, Dr. Watson. I believe you may draw your conclusions after what you've seen today. Fortunately for your kind, there are laws in place to prevent the most virulent excesses of such zealots. But even more than laws, my family feared the loss of face. That most British of concerns: what would our neighbours think? So, rather than using magic directly to kill Artemisia, they would lower themselves to get a muggle to do it for them. Hire thugs, lowlifes. Anything to avoid risking the involvement of the Ministry of Magic and the following scandal."

"I despaired for her life. I could not protect her all the time, not while I tried to gather enough of my fortune that we could safely travel to America and build ourselves a new life there. And I feared that had I used any common magic to try and deceive them into faking her death they would have seen right through it. Our family isn't powerful for no reason. Power comes from knowledge, among wizards."

"So, what did you do? And why did you involve us?," I asked.

"I went dark, Dr. Watson. Darker than I could ever imagine myself going, darker than even my family would dare go or guess," he replied. "If I could not fake Artemisia's death, I would not. I would let them kill her for real, and do so with a most reputable witness, in a way that would leave the muggle authorities absolutely no doubt about what had happened, so that none of my relatives would feel the need to investigate further. But before letting her die, I would have done something to keep her soul anchored here, to this mortal coil. And I would eventually bring her back."

And to these words, he drew out the emerald necklace, and dangled it in front of us. I felt dazzled, nauseated. I am not an especially religious man, but the sense of the kind of blasphemy that he was hinting at stunned me. Not only that, but seeing the necklace myself made it all come back. The dreams. The vivid visions of Artemisia Cooper, screaming for help, her last minutes on Earth spent in pain, bleeding out on a bed, alone in her room, her life escaping from a bullet hole. Those had been no ordinary nightmares - they were memories. Memories of a lost fragment of a soul, trapped in a gem, screaming out and touching the closest minds it could reach.

I was seething with rage and sorrow. "You did that to her," I said, "and you say you love her?"

"She agreed, Dr. Watson. In fact, she came up with the plan," he replied, unperturbed. "The bravest of women, my Artemisia. She did not want me to risk any repercussions from my family had we gone with less safe a plan. Of course, it wasn't cheap. A second chance at life is an expensive thing to buy. It required another life, to even the balance on the Grim Reaper's ledger."

"And that was the first assassin," concluded Holmes.

"Indeed," Malfoy nodded. "I was with her that night. She killed the thug and we performed the ritual. A beastly man ready to murder a young woman for coin he would then go and spend on liquor and opium. You will forgive me for thinking he will not be missed, and she did this city a favour by ridding it of him. The rest of the story, you already know. Our only mistake was involving you. Artemisia said you were famous - she's an avid reader of your sensational tales, Dr. Watson - and thus would be the most credible witness imaginable. I did not think you could also be so sharp as to fool even the Imperius Curse. I guess for all that I've been trying to distance myself from my family, I still have to learn to respect you muggles and your abilities as much as you deserve."

"What about the second assassin?," I asked.

"Without any doubt, a man of similar worth as the first one - that is, none at all. My family was not keen on getting involved personally in any obvious way. He will have been hired through two or three indirect steps. I don't believe a detective as experienced as Sherlock Holmes should have any trouble finding him and securing him for the gallows as he deserves. But I have not concerned myself with him, as he only was a useful tool for our plan."

"And now, the choice rests with you," he concluded. "You may disclose this information, in the hopes that the political fallout will destroy my family, who commissioned Artemisia's murder. But I doubt they would be in that much trouble, as the evidence is so slim, and all you would obtain is either chaos that will be detrimental to both ours and your world, or to be tied in straitjackets and dragged to the closest madhouse. And worse, both me and the revived Artemisia would be in danger."

"We will not speak of this," said Holmes. "We will not disclose any of this story. Dr. Watson will not write about it. We will keep the matter private."

The wizard smiled. "I trusted as clever a man as you to immediately come to that conclusion. Yes, that is the best path of action for all of us. So, I bid you goodbye. I will go live what I hope will be a quiet life with Artemisia across the ocean, and I wish you the best. I must thank you for helping me reunite with her, even if unwittingly. And now, for one last trick..."

And with that, he gave a small bow, and suddenly his own imagine was twisted, like a reflection in a rippling pool of water. It was as if he was liquefied and sucked into some invisible hole at the centre of his body, and one instant later, it was as if he'd never been there, leaving us to question our own eyes.

These were the facts of the case of the emerald necklace, in which we faced forces beyond what we ever believed to be possible. After that day, we never talked about it again, and pretended it had not happened even among ourselves. I suspect Holmes was especially upset by learning about magic because of how it affected his own profession. How could, after all, one be a detective and practice the science of deduction in a world in which such forces allow some people to go as far as twist matter and play with memories? But as none of the cases we were faced with in the future seemed to involve any culprit with supernatural abilities, this worry eventually subsided in him. As for me, I am still struggling with those memories; perhaps it is why I am somewhat breaking my own promise by putting them into writing. Even without the influence of Miss Cooper's soul close to me, I still dream about her sometimes, and wake up in fear in the middle of the night. I was never a man of certainties on matters of the spirit, but this incident only laid my questions bare and forced me to face them. I can not find comfort in either science or religion, as they are both blissfully ignorant of so much that I saw and experienced on that day. When walking through London, I look at those that walk next to me with new eyes. Sure enough, now and then, I think I see someone holding a wand in their hand, barely concealed, and quickly avert my gaze and walk away.