Left alone in the dark foyer, I found that I could not stay there. The 'haunted house ride' aura which I had found it full of in my first visit, five nights before, was as nothing to the darkness which then filled it. Besides which I felt I could not bear my own company. Quickly, like a child who was afraid of the dark, I made my way to the room set aside for Mary, Shirley, and myself.

An oil lamp burned low on the bedside-stand, but they were quietly sleeping. From the book lying open on the covers (I recognized a collection of fairytales that Hermione carried about) it seemed that Mary fallen asleep while waiting for me. A sleeper's smile rested on her face. She was, perhaps for the first time in days, sleeping peacefully. I hoped I would not wake her; I didn't need to poison her contentment.

She was sleeping on her right side, and her left ear poked up above the locks of blond. Even in the dim light I could see the kink in the lobe where the umbilical cord had wrapped around her infant head – and nearly strangled the life out of her. So nearly dead. So nearly lost to the world. Taken from life before her life had begun. Mary, an infant, just turning into a creature of the light and air. Harry, a child, on the cusp of becoming a man.

Harry had a sweetheart too; Ron's younger sister, Ginny Weasley. Too young to accompany the trio. So precious her kisses were forsworn. Not while he carried danger with him. Sweet sixteen.

I was to get no sleep that night. The terrible secret which Sherlock Holmes had revealed to me, and still more, the solution to it which he theorized was all but inevitable, kept me up all through the dark hours, while the clock in hallway below rang out the quarters in harsh clangorous notes. It was not primarily grief that I was feeling. I had – over the past week – become fond of the boy. But what I primarily felt was an overwhelming sense of wrongness. If Harry were to die, it would be a tragedy. That Harry had to die ... there lay the sting. Sherlock's insistence that hope had merely been rendered implausible and had not yet been truly ruled out struck more of desperation than of hope.

When the grey light of a sunless dawn crept over the room, I gave up my attempts to doze, and arose for the day.

Sherlock was searching for a solution in the facts of the witchery itself; in the hope that those who knew how to do this terrible thing might also know how it could be undone, in the hope that an understanding of what exactly it was would give him an insight on how to get rid of it.

I knew nothing of magical theory, dark or light. And from the time that Ron and Hermione told me Harry's tale, I had believed that the situation was too alien to my own field of study for my knowledge to be of much use in the matter. Yesterday, I had resolved to make some attempt to do such as I was able to in spite of my insufficiency. Today, the fact that I was ignorant no longer excused me. That I must act, that I must do all that was in my power, had become inescapable. And strangely, the very fact that the injury – if I may still call it that – was so much greater and more horrific than I had suspected, made it seem less likely that the causes would be elusive. Surely the internal causes of so terrible a condition, if they were such as could be discovered by a physical examination at all, would be blatant and unmistakable.

But there was still my own ignorance of Wizarding science. Perhaps the Order of the Phoenix had a doctor in its ranks. Perhaps, between the two of us, something could be done.

I was startled from my train of thought, and the rest of the house roused, by the ringing of the newly installed doorbell.

The foyer was filled with people. Lupin was there, but this time there was a young woman by his side; her bright pink hair and her youthful rounded cheeks providing a striking contrast to him, with his greying hair and face, and lean frame. More red-headed Weasleys were there. The Mr. and Mrs. of the family were a very pleasant middle-aged couple; the Mrs. was plump, the Mr. was balding, both were cheery and friendly as could be. Mr. Weasley in particular seemed absolutely delighted to be introduced to Sherlock, Mary, and I – the notion of a muggle detective and two muggle healers appeared to utterly fascinate him. Three more of their children accompanied them. They seemed to be a very large family. One was a full grown, stocky looking fellow with a grin reminiscent of the twins. Another was a tall young man with a face which would have been remarkably handsome if he had not been so badly scarred – it looked as though he had been mauled by an animal at some point. His wife had come too, an ethereal beauty floating along on a cloud of platinum tresses. The third, a lithe young lady, all flashing eyes and flaming hair, was clearly Harry's Ginny, the youngest Weasley and the only girl in the family. Though too young to be a member of the Order, she had accompanied her family to London. Kingsley Shacklebolt was there. This sage and knowledgeable correspondent turned out to be a large and majestic black man, looking like one of the Three Kings out of the east in his rich resplendent robes and gold jewellery. And there were others who I had not met or heard of before. I noticed that Mundungus Fletcher was not among them.

Only a handful of them had heard the plan. Shacklebolt, current head of the Order, had summoned them here for a meeting in order to discuss it. Some of them, unlike Mr. Weasley, were decidedly disapproving of the presence of Sherlock, Mary, and I. There were whispers of spies and possible obliviations. But Harry would hear none of it, and defended us vigorously. I remembered the suspicion with which he had first listened to us. It was gone. And he seemed to be riding on a wave of exhilaration. His smile, aglow with focused excitement and open camaraderie, innocent and straightforward and unaware, cut into my heart. I felt stained with intended treachery, with ugliness in mind and as yet unshed blood on my hands.

Before the meeting, there was a minor uproar. Ginny, at sixteen years, was still considered a minor by the wizards, and her mother would not let her even be present at the meeting. Ginny thought this tremendously unfair, and said so very plainly. But Mrs. Weasley was unswervable on the matter. Ginny was left behind in the foyer with Mary to bemoan her non-inclusion (I had no doubt but that she would find Mary a very sympathetic companion) while everyone else went down to the kitchen.

Sherlock Holmes presented his plan to the Order of the Phoenix with a brisk practicality in which the extreme melancholy and half-hidden desperation of the night before was indiscernible. The point of precisely how capturing the cup of Helga Hufflepuff would help destroy Riddle was left vaguely relegated to it being 'Dumbledore's Orders, as Harry had insisted. But with the exception of that one important factor, he was extremely clear, and explained to them in great detail every point about the strike-team and the plan proposed.

Harry was eager to move on the plan without delay. We had met him in a paralysis of uncertainty. He had not known what to do with the information, how to proceed on a task that seemed just too big. He was a man of action; like me. And now, seeing a path clear before him, he wished to move now – tomorrow, as soon as the Order and the Strike-team could work out their co-operation.

Sherlock did not present any reasons against this. The Order was rather shocked, as Ron had expected, and not perhaps extremely pleased, by the notion of a joint strike team. But they took Harry's word as if he was their head, even though he was not even officially a member yet. And the situation was such that they hesitated to turn down any strategy which might stand a chance. Mr. Shacklebolt expressed frustration at the proposed team's ratio of wizards to muggles. So Fred and George suggested that the older members of 'Dumbledore's Army' could be called upon. In spite of its imposing name, Dumbledore's army turned out to be a school club, started for the extra study of practical fighting techniques in anticipation of Riddle's rise to power.

It was decided that the Order would go now, guided by Sherlock, to meet with the muggle strike-team and prepare for the operation, which was tentatively planned for the very next day. The five of us would search a few more crime scenes, then we would all meet again in the afternoon, at a location yet to be decided.

Before we left the Black mansion, I managed to get a word with Remus Lupin about finding a trustworthy Wizarding doctor. He was very sympathetic, but did not seem to think that it was a very good idea. It was a scar. There was nothing to be done about it. I did not speak the exact nature of my concerns, but I was able to convey to him some of my urgency. He said that he would talk with some of the others, and if possible, bring someone to the meeting later on. I would have preferred it if someone could have been found immediately, I wished to start as soon as possible. But this did seem to be the best that could be arranged.

Whether because we had already gone through most of Sherlock and Hermione's list or because Sherlock and Hermione had become so very certain of where the horcruxes were to be found that they had trimmed their list down to only the most important places, our search was not long that day. The last site we searched was a dreary old corner by an abandoned house where a Wizarding special forces agent, had been killed years before. We found nothing of course; all the crime-scene searching we had done had been completely useless. It was still several hours till we were supposed to meet the strike-team.

Sherlock retreated into the old falling down house, out of the weather. Here, further north than London, it was drizzling quite badly. The day was grey and mournful. The wind had blown itself out last night and though it seemed that it must have rained hard earlier, there now was nothing but a steady drip, drip from eaves and tree branches. The sky was dark. It could have been been nearly twilight, even though my watch said it was short of one o'clock. Nothing rustled or chirped in the dark thickets on either side of the path I had aimlessly meandered down; just the steady drip drip drip. There was such a lot of dead wood. Dead. Dark. Cold. So unseasonably cold. I pulled the zipper of my light summer jacket up at little higher, wishing I'd brought something heavier. The hopelessness of the whole situation was forcing itself upon my soul, the hideousness. And I couldn't go back. Go back before I'd heard. I couldn't get back what the world had been then. I couldn't wipe it clean from the horror of those few little words. Now it was dark. All was dark. Nothing was bright and good any more, all soiled, twisted, darkened by this ...

My knees gave way beneath me and I stumbled for a moment, catching myself with one hand on the damp stone path. There was mud between the stones. My breath steamed in the raw and bitter air. The little winding path in amongst the rhododendron thickets had taken on a strange quality. It was not merely dark and forbidding. Every branch, every dripping twig, the gleaming stones amongst the moss, seemed a terror. Unreasoned fright seized me. I turned round and started to run. But I didn't know quite where I was running to. Horror of my destination crept over me, revulsion, terror – I couldn't go that way. My steps faltered. Cries were rising in my mind, remembered cries and the groans of wounded men. The world was so cruel. The world was so dark. What did it matter if I saw the sun, when such things existed beneath it. Distantly, like something coming back from a dream, I heard gunfire and screams, saw a man falling from a ledge. I saw the face of a murdered woman. A weeping child, weeping and weeping and weeping. Some little corner of my mind, quiet, still sane, ridiculous in its tiny impotency against the enormity of the horror and despair which filled me, said 'Stop it. Now. Get up and go back to the others.' A flickering candle against a wave. I was powerless to obey it. No little stirring of my paralysed will could stir my frozen brain and swamped imagination, or fight off the billows of darkness which were overcoming me. Panic gripped me. I was drowning; drowning in the freezing darkness. Was I sinking away? 'Good bye, John.' No, that was long ago. If there had been air in my lungs I would have screamed. I couldn't see, swirling blackness obscured my eyes.

Light. Piercing, blazing, flashing, blinding light. I recoiled as though from a blade. As a cold hand from hot water. But it was all around me. I breathed again, deep breaths of the warm, wet air. Did I say the air was cold? The air was warm. It was one of those sweet summer showers, gently seeping into the grateful, dry earth. Rain-drops pattered off leaves and splashed among the rocks. The smells of damp grass and yellow iris came through the rain.

I sat up. Harry's silver hart, burning with radiance, stood above me like a sentinel guardian. The raindrops caught its light and fell like gleaming jewels all round us. Its limpid eyes were glowing with sympathy and concern.

And then it was gone. There was the sound of feet and Harry himself came running along the path, his wand still in his hand.

"John! Doctor? Are you all right?! How long were you there?"

"I ... don't quite know."

He gave me his hand and helped me to my feet.

"That was quite a lot of dementors. I'm sorry, I should have warned you that there might be some around a place like this."

"Dementors?"

"Yeah. They're massing you know. Usually they either hang out alone, in lonely places, or else work in groups for the Ministry of Magic. But Riddle's got them packing up and causing trouble." We were by then walking back along the path to the house, as Harry went on about these invisible beings (invisible to me anyway) called dementors by whom I had apparently been under some kind of attack. He inquired several times if I was really all right, and asked if I had any chocolate about me. "... chocolate's really good for recovery after dementor attacks." he assured me.

I felt strangely weakened and was keenly, painfully aware of what it was that Sherlock and I were doing. The very concern in the remembered eyes of the hart seemed to reproach me. And he, poor fellow, was completely unaware that his companion had such notions in his head.

Suddenly, some of what he had been saying solidified in my mind.

"Azkaban? ... Did you just say they guard Azkaban – the Wizarding prison?"

"Yeah." said Harry.

I stopped, aghast.

"Er, well," he continued, "they were actively attacking you there, and they couldn't exactly do that to the prisoners, but, yeah. ... Dumbledore was always trying to get the Ministry to stop using them. But ..."

Something had occurred to me.

"Harry, if we hadn't heard her, what would have happened to Mary?"

For a minute he didn't answer. Then he nodded.

"I'm afraid – yeah. She probably would have."

The dementors might have been back, I had certainly grown cold enough.

"John," said Harry, a little hastily, as if my face alarmed him, "John, it's ... People usually survive Azkaban. I've had friends who were sent there. They came out okay, er well, not great, but they recovered. And, at this rate, Mrs. Watson's probably not going to get caught."

"They sent children?" I said. "To a place surrounded by those ..."

"No. One was the Hogwarts gamekeeper. And then there was ... Sirius."

I remembered the particular vehemence of Harry's insistence that Sirius had never had anything to do with Riddle's gang.

"Was he accused of being a Death Eater?"

Harry nodded, his jaw strangely shifted. It was evident that the subject was extremely painful to him.

"So it's the high security prison?"

"... It's the only prison."

Suddenly, I went from cold to hot.

"Everyone who's sent to prison has to endure them?"

"Yes." said Harry.

"Everyone? What about all those muggle-borns – what about the students?"

Harry did not immediately reply. He looked as sick with anger as I was.

"If nothing goes wrong, they'll never get caught." There was a quietly inexorable determination in the young man's voice.

The sound of laughter broke incongruously upon our ears. Ron and Hermione were laughing on the decrepit porch, out of the rain; the pure-blood and the muggle-born, hand in hand.

"Maybe Hermione has some chocolate." Harry said.

Off he went to them. I watched him run across the overgrown lawn to his friends. I checked my watch. It was still a long time until we were supposed to meet with the Order. I wasn't going to wait any longer. I took the side door into the old house, to tell Sherlock of my plan.

There he sat, his long lean figure bent over the table, his sharp features illuminated by the single lamp as his keen eyes scanned the brown and crumbling pages of Hermione's Secrets of the Darkest Art. Instantaneous, unreasoned revulsion and fear went through me; anger at the cruel book which had wrought such pain and destruction, horror at the sight of it in Sherlock's hands. It would have caused me less repugnance if it had been a coiling adder – written by those who courted the infernal, revelled in the foul, murdered and distorted and ... Something snapped.

"Sherlock Holmes, put the damn book down!"

He lifted his head from the page, and looked at me keenly for a minute.

"An admirable choice of words, John." he said finally. "It is a damned book; indeed, it is the very damnedest book it has ever been my lot to peruse."

I looked away in great vexation of spirit, not knowing how to answer his calm agreement. But before I could pick up the train of my thought again and approach the subject of a medical examination, he was speaking again.

"John, do you know why I'm bothering to work through this?"

"Yes, I do."

"I take no pleasure in this hideous book. Its very lettering is vile. I'm trying to fix a problem I didn't create! Do you think I want..."

"No! Of course I don't, Sherlock! Of course I don't!"

He turned feverishly back to the book, shuffling roughly through the cracking pages and talking fast.

"I've looked, and I've looked, and there is nothing, nothing, about living horcruxes. I can't even discern whether horcrux specifically means the segment of soul, or whether it means the entire device, both segment and vessel. The pain resulting from the horcrux is specific to a certain area, but does it then follow that the segment is specifically located in the area thus affected? Is it located specifically enough for a physical removal? If, on the supposition the segment could be thus physically removed, would it even be possible to do so without causing lethal damage? Could it be detected as an object within the vessel – which could then be separated out? Or would the entire area have to be removed? Or are we working on a false hypothesis? Is the head pain merely symptomatic, and the causative segment diffused throughout the vessel? I've had blood and DNA tests done on him, and they checked out fairly normal. Or, normal in and of themselves ..."

"You have? When was this?"

"Oh, the other day. He doesn't know about it. I've had them evaluated by a number of different specialists."

"What do you mean normal 'in and of themselves'?"

"I mean they would seem normal ... if it wasn't for Riddle's DNA. You know I managed to get a DNA sample in Amelia Bones' house."

"But Harry can't have some of Riddle's DNA. If the bit of Riddle was plainly there in Harry's very genetic code, you wouldn't still be asking where it was."

"No. Harry doesn't have any of Riddle's DNA. It's actually quite the opposite. Riddle has some of Harry's."

"What?!"

"Harry's is normal, undamaged, completely unsurprising DNA. Riddle's is decidedly abnormal. When they said it was artificially engineered, it explained much. It is a completely unnatural, indeed naturally impossible, phenomenon."

"But what does this have to do with Harry's DNA?"

"Well, Harry mentioned the other day that he was present at Riddle regeneration."

"Yes."

"But at the time he didn't get too terribly graphic about what actually happened."

"He, or Hermione, said that Riddle kidnapped him for political reasons ... meaning to murder him in front of the gangsters."

"And that was true, so far as it went, but it wasn't the whole story – nor even the main point, I believe. ... I don't claim to understand how what he did worked. But Harry's blood was used somehow in the regeneration process. Apparently Riddle needed someone's blood, and thought that using Harry's would get around the effect of the uh, 'spell' that Lily cast on him years before, by extending its protection to both of them ... or something. Anyway, it worked. Obviously. Harry hasn't had that protection from Riddle since."

"Has that been actually proved?"

"Yes, it has. I understand Riddle went to some lengths to prove it ... he tortured the boy, I'm afraid. ... But that is entirely beside the point at the moment, because that isn't the horcrux. It runs in the opposite direction. It's not a element of Riddle in Harry. It's a element of Harry in Riddle. So back to the element of Riddle..."

So that was Harry had been doing there. My mind flashed to some lonely little dingle, where the boy of fourteen, kidnapped, wounded, doubtless bound, in searing pain from the proximity of the sorcerer, watched as ... fire, steaming cauldrons, goblin men, witches chanting foul incantations – vague and ghastly images swirled in my imagination. Through the nightmare sounds in my mind, I heard Sherlock continuing.

" ... Of what nature is this segment? We know that something of Riddle is inside Harry, but we don't know exactly what. Wizarding theory says it is a fragment of soul. If," and he lay great emphasis on the word, "if that is in fact an accurate way to describe it, then it is beyond my purview, and yours too."

"But you do not believe that it is."

"I admit that I have a certain very strong disinclination to accept such a theory."

"On the other hand, a bit of ... brain material transplanted into someone else's mind would hardly cause the effects on Riddle that we see. I mean, we're talking about unnatural prolongation of a mortal life. ... Or perhaps not even really that ... If that doesn't fit into the category of ..."

"You quite hold the supernatural theory, I see."

"No, Sherlock, I'm just trying to understand what's happening."

"Well, so am I. And that's why I don't put the damn book down."

"Well, you do that. I'm going to take him to the hospital. If he has a foreign object embedded in his skull, or wherever, which isn't supernatural in character, I should be able to detect it. And if I can detect it, then maybe I can remove it."

"The ability to detect it hardly guarantees the ability to effectively remove it, as many cancers prove. Still, use every device that modern science can suggest to discover if there is anything which can be removed. ... Anything which could possibly be the causative agent. I have some notes ..." he produced a wad of notepaper, thickly written in his bold, distinctive hand. "I've jotted down the facts which seem as though they might be of use to the medical investigator. I intended to get someone connected to the Order to accompany you and Harry when we met with them later today. But if you wish to go now, by all means, do so."

"I did ask Remus Lupin to try and find a Wizarding doctor, to come and look at him."

"If he has managed to engage one, I shall certainly send him on to the the hospital."

"This is supposing of course, that I can get Harry to come."

"Why not? He certainly doesn't like having the connection. How could it hurt? And he likes you well enough. We are now waiting on the combined strike to team to be ready, and cannot proceed any farther with our plan until tomorrow morning at the very earliest. He has the time. Your personality engenders confidence. Go. Convince him. I'll continue looking for a solution within the Wizarding world. ... Surely, surely if Dumbledore knew – and he obviously did – then he must have had a plan either for Harry's cure or his informing."

"But he was killed."

"Yes. Pity, that. Therefore he must have told someone else his plan."

"Not necessarily, Sherlock. People don't generally plan on being murdered."

"Well, I think this one did. ... Oh, and John, do pick up some duct-tape while you're out."

"Duct-tape?"

"Yes, duct-tape. Is that a problem?"

"No."

"Well I think it might be a good idea to have some."

"...We couldn't just put the whole thing off for a short time?"

"The wheels are in motion. A great deal is at stake. Even if there weren't, there's only so many alternatives we can look into. I don't think a few extra days would help us much at this point. And much evil can happen in that amount of time. Harry is intent upon moving as soon as possible. Shacklebolt is intent upon moving as soon as possible. Mycroft is intent upon moving as soon as possible. And I wouldn't stop them if I could. ... Unless, of course, you actually do find something. Then I'll get this put off long enough for a proper operation, even if I have to tell the whole Order of the Phoenix everything."

I left Sherlock alone with his volume – I now saw that there were a number of others beside him, doubtless procured from Hermione's marvellous bag – and went back outside to look for Harry. He met me at the door with a bar of chocolate.

Harry was right. The chocolate did help. But the examination was as useless as could be imagined. For all that I could tell, Harry's scar was just that, ordinary scar tissue on the skin of the forehead. Scans revealed no tumorous tissues or foreign objects in his head, or anywhere else for that matter. Brain imaging showed no unexplainable phenomena, no suspicious activity.

The Wizarding doctor did come. In the middle of the afternoon I got a call that a pair of suspicious characters were down in the lobby asking for me. It turned out to be the senior Mr. Weasley with a young wizard named Augustus Pye. He was an agreeable, open minded fellow, who seemed pleased rather than otherwise to be working with a muggle. The problem was he clearly didn't have a clue about Harry's injury. He, like every other wizard in the nation, knew about the famous lightning scar. But he had never heard of any complications surrounding it. And worse, he seemed to assume, from the immutability of the curse that had caused it, that nothing whatsoever could be done about the complications. He examined Harry, questioned him, and expressed sympathy at his condition, but he did not seem to comprehend the gravity of the matter. Finally, I took him aside, well out of Harry's hearing, and explained to him that it was believed or feared (I did not say by whom) that Riddle had transferred a part of himself to Harry at the time of the scar's formation.

I had been hoping that he would laugh at the notion, and give some Wizarding explanation which would explain Sherlock's terrible theory completely away. But he didn't. He took the theory very seriously indeed, as if it were entirely plausible notion under the circumstances. To my distress, he took as a given that if that were true, no action of ours could help him. Much more sober than he had come, Mr. Pye left, promising to consult those more specialized in that area of Wizarding science than himself, and get back to me before the morrow.

In the hospital, we kept on. I swore that Harry should not die due to some slight carelessness or lack of attention to detail on my part.

Twilit day had turned to dark-black evening when the door opened to admit Mary, blooming and bonny. There was a pearlescent gleam at her neck and wrists, and the salmon material she was clothed in fluttered about her elbows and her knees. Her wide blue eyes gleamed in the fluorescent lights as she tripped lightly over to kiss me.

Behind her followed a young woman, who, on second examination, turned out to be Lupin's young wife, who I had met that morning. But her bright pink hair had been turned to a quiet shade of mousey grey, and her little button nose had grown, for all the world like Pinnochio.

"Hullo, Doctor." she said. "Wotcher, Harry!"

"Come to say that Harry's been out too long?" I asked her.

"Nope! We've come to keep him out later." she said cheerfully. "Or at least that was Mr. Holmes's idea."

"What do you mean?"

Mary pulled several stubs of paper from her purse; concert tickets. I remembered Sherlock excitedly purchasing those over a month ago; three – for himself, for Mary, and for me. I had forgotten that it was tonight.

"Are those Sherlock's tickets?" I asked.

"Yes." said Mary. "He asked us to make sure they didn't get wasted."

"But, surely he's going himself?"

It was true we were in the middle of a case. But Sherlock had a truly remarkable power of detachment. If he knew he could could do no more on a case for a period of time, he could, and often would, turn his mind completely to something else, whether it be music, or chemistry, or medieval pottery. Many an evening we had spent in concert halls, Sherlock Holmes floating happily off to music land, while I, of less flexible turn of mind, missed half of it because I was so emotionally and mentally caught up in an investigation. So I was surprised that he was not going. I remembered the great enthusiasm with which he had announced the event. He had said himself that we could not proceed farther on the case until tomorrow, and that there were limited avenues for horcrux investigation.

"He says he's too busy." said Mary. "But he insisted that I still go. He thought Harry might like to have the third seat."

"Oh, no." said Harry, looking at me and Mrs. Lupin. "I'll apparate back to Grimmauld Place. You three can have the tickets."

"Sorry, Harry." said Mrs. Lupin. "But the Order sent me along specifically because of you. They weren't too pleased about you being off by yourself for so long. Where you go, I go."

"And I'm sure we can get a fourth seat." said Mary.

"Well, I really can't go anywhere at the moment, anyway." I said. "Where is Shirley?"

"With Sherlock. He said he wasn't doing anything dangerous tonight and could look after her just fine. Are you sure you can't come?"

"Yes, I'm afraid I really couldn't justify leaving right now." I replied, thinking of the long evening's work ahead of me.

She was clearly disappointed "You and Sherlock. ... Are you all right, Love?"

"Yes. I am. Just fine."

"He was attacked by dementors." Harry supplied helpfully. "That would leave anyone a bit shaken."

"What are dementors?" she asked.

"They're terrible beings of the dark and decaying places." said Harry. "He stumbled right into a whole bunch of them."

"And they attacked him?"

"Yeah."

"Yes, you should ask him to tell you about patronuses, Mary. Get him to show you. Find some out of the way place for a demonstration, Harry, I'd like her to see. ... But you three had better go, or you'll be late. Run along. Enjoy yourselves."

She suddenly leaned over, and, very softly so that only I could hear, she asked: "John, is there anything I can help you with?"

"No, I just ... Yes there is. Observe Harry."

"Why, John, you have been working with him all day, haven't you? How should be able to find out more ..."

"I'd just like your instinctual opinion."

"Do you want to prejudice my instincts by telling me some of your research, maybe?"

"No. I'd prefer to keep you unprejudiced."

As they bid me goodbye, Mary with a kiss and Harry thanking me for the exam – nice of him, as I hadn't managed to help him a whit, I tried not to think of how much I would have preferred to spend the evening out listening to classical violins with Mary and Sherlock.

Left alone to restudy the data, I plugged away, deep into the night. Long after the concert must have ended, there were more footsteps at my door, a firm, slow stride, and a toddling little patter. The door swung open and Shirley ran in, crying 'Daddy!' and climbed up on my lap, trying to tell me in childish syllables about all the crazy people she and Sherlock had been talking to. Sherlock followed. He stood quietly next to the desk while she babbled happily on, occasionally agreeing with something she said, and backing her up on just how ridiculous such-and-so's hat had been. When she finally stopped for breath, he turned to me and said:

"Call it a night, John."

I turned back to my desk.

"I ... haven't got anything."

"I know. And neither have I."

"Nothing?" I asked. "Sherlock, do you mean to say ..."

"No I don't. Not tonight, anyway. ... My dear fellow, don't despair yet – time enough for that later. And perhaps I shouldn't say that I have nothing, for now I know at least who knows nothing, and that is, after all, something. We are not totally without recourse yet, and I will be very much surprised if tomorrow does not shed some light on the matter. Come now, you've done what you could. It won't help anything if you aren't alert tomorrow."

"The operation is on schedule then?"

"Yes. We start in five hours. We should be in possession of the bank no later than six o'clock tomorrow morning, and to Hogwarts School before ten o'clock. ... That is, if you still want to help in this outrageous affair?"

"Yes, of course I do."

Sherlock paused.

"Shirley," he said, "look."

"What?" she said, looking around.

"There. Out the window. Do you see the helicopter? Just like the ones Mr. Beaumont showed us? Go and see."

Shirley hopped down and ran to the window to watch the aircraft. Having thus distracted her, Sherlock turned back to me and spoke in a lower voice.

"John, I'm having serious misgivings about asking you to come tomorrow. I think you should know – Harry's right. The chances are very poor that we'll all survive the operation, even supposing we find a way to save him."

"Is that supposed to make me let you and three teenagers go alone? And anyway, I thought you needed me there as back-up."

"But in doing so I'm scarcely treating you any different from that treatment of Harry which you so deplore."

"Surely that's an exaggeration."

"I'm afraid it really isn't. Yes, it may matter a great deal to have someone there who I can absolutely depend upon. But, depending on certain variable factors, it may also prove irrelevant – and result in nothing but another pointless death."

He glanced over to where Shirley was playing by the window.

"You could've dropped Shirley off at the Black place before you came." I said. "You didn't even need to come in person, you could've sent a text. You brought my daughter to this conversation on purpose didn't you? Make me think twice about going to face down the big bad wizard, hmm?"

"Yes." he admitted. "I did."

"Well – if I get killed tomorrow, Uncle Sherlock's going to have to help Mary look after her. ... Shirley! Come on, Sweetie, time to go back to Harry's house."

But as it transpired, we did not return to the Black place that night. Sherlock lead us down by the river where the combined strike-team had set up a temporary base of operations. He had spent most of the afternoon and evening there, among the Order. And he knew those parts better than I knew my own neighbourhood. But I don't believe that he would ever have found it again if Arthur Weasley hadn't been outside waiting for us. There, under the corrugated roof of an empty warehouse, a large and motley company was assembled; muggles and wizards, men and women, sober adults and excited teenagers, piles of the the slim little aerial broomsticks and two large gunned helicopters.

Whatever their hesitancy about the plan might have been, it had now been cast aside. All was set. Kingsley Shacklebolt had altered it to the effect that only half of the strike-team would follow us up to the school in the north. He would remain behind with the other half in London, ready to take action here, ready to fly in to the assistance of the un-enchanted at the Ministry of Magic as soon as Riddle was gone and his spells were broken.

They waited only for the morrow.