I've just been having a bit of fun writing this chapter, so I hope you enjoy it. It draws very heavily on The Empty House - do you know, I should have made this a crossover, I'm sorry. The parts in italics are from that brilliant Conan Doyle short story, so I cannot lay claim to them, much as I wish I could - and you are warned that there are MAJOR SPOILERS for that story in this chapter.

She didn't show John The Empty House. Of course she didn't. She didn't even mention it to him. It had upset her, she could say that much. Yet she could not deny that it has fascinated her, and that it would keep returning to her thoughts long after she had resigned it to the bookshelf, next to A Study in Scarlet, and alongside a good many other books that brought back mixed memories.

John – yes, indeed, John. It was two and a half years since he had left the house with scarcely a word to his landlady. Ever since then he had been worryingly silent – not a visit, not a phone call, not even a text. Nothing, except a single letter addressed to Sherlock that she had ended up leaving on the coffee-table in 221B: she didn't want to think about what he must have written in it.

And he surprised her by turning up out of the blue, a hesitant smile about his lips – and there was another thing about his lips too, a rugged greying moustache that didn't suit him in the slightest. It made her think of his Victorian doppelganger somehow. But yes – John had changed, changed perhaps more than she might have guessed, and though she was delighted to see him, it was with a sigh of something akin to regret that she welcomed him in, a sigh she had to hide.

They conversed briefly. It transpired that John had met a woman whom he was planning on marrying. Mrs Hudson couldn't deny being a little surprised – a woman, indeed! – but congratulated him warmly; he promised that he would keep in touch; and then, for a second time, he left. And this time it was certain that he wouldn't be coming back, not to live here.

Never had the title The Empty House been more applicable to current events. As the door closed behind John, Mrs Hudson's eyes fell on the book on her shelf, and she smiled sadly, as if she could not quite believe what had just happened.

I struck against an elderly, deformed man, who had been behind me, and I knocked down several books which he was carrying... I endeavoured to apologise for the accident, but it was evident that these books which I had so unfortunately maltreated were very precious objects in the eyes of their owner. With a snarl of contempt he turned upon his heel, and I saw his curved back and side-whiskers disappear among the throng...

'Can I help you with anything, sir?' asked an unnecessarily irritating French accent at John's side. John waved dismissively, his eyes still in front of him, not even casting a glance at the black-suited waiter leaning over him, and asked for a bottle of champagne.

As is the wont of waiters, the man began to list the merits of certain vintages, and pointed out his favourites on the menu, whilst John managed to ignore everything he was saying, seeming to become more nervous with every passing second. The woman across from him watched him in mild amusement.

The waiter said something about the quality of surprise in a certain champagne. John shrugged dismissively: 'Surprise me.'

The waiter murmured something under his breath and turned on his heel, before disappearing through the crowded restaurant.

I had not been in my study five minutes when the maid entered to say that a person desired to see me. To my astonishment it was my strange old book collector, his sharp, wizened face peering out from a frame of white hair, and his precious volumes, a dozen of them at least, wedged under his right arm.

He was steaming unsteadily towards the moment, and he hoped that his red cheeks weren't too much of a giveaway. Did he mean to surprise Mary? – perhaps. But the girl was intelligent. God, she probably already knew what he meant to ask, and was just humouring him with that smile, that naïve twinkling gaze. Was he taking too long over it? – How was he supposed to know? He'd never done this before – never asked someone to –

The wine-waiter appeared. He thrust a bottle under John's nose, forcing him to read the label. He nearly read it out to Mary, such was his lapse in concentration. God, not now...

'With five volumes you could just fill that gap on the second shelf. It looks untidy, does it not?...'

'It has all the qualities of the old, with some colours of the new – like a gaze from a crowd of strangers... suddenly one is staring into the face of an old friend...'

I moved my head to look at the cabinet behind me...

He looked over the top of the bottle, tried to ignore it, tried to catch his previous train of thought...

When I turned again Sherlock Holmes was standing smiling at me across my study table. I rose to my feet... and then it appears I must have fainted.

When he turned again a familiar face was looking down at him, smiling. He rose to his feet, shaking all of a sudden, starting to come over all faint.

'Holmes!' I cried. 'Is it really you? Is it possible that you succeeded in climbing out of that awful abyss?'

His mouth formed silently the word How? Mary stared, asking John what was wrong, what was going on.

'Well,' said Sherlock Holmes, blushing a little, 'short version: not dead.'

'I came over at once to London, called in my own person at Baker Street, threw Mrs Hudson into violent hysterics...'

She had gone to re-read The Empty House without quite knowing why, still pondering as she did over the re-appearance of this Holmes. His explanation of his survival had been plausible. After all, he had gone over a waterfall, not a building, and there are many irregularities to waterfalls. And nobody had seen him fall. Not like when –

She was just going to replace it when she heard a noise on the front step. She didn't often get visitors these days, and she got up, perhaps waiting for the bell to ring or a knock to resound, when she realised that the handle was being turned, the keyhole wrenched. A gasp sprang to her throat – someone was trying to break in!

In the blink of an eye she went through the kitchen, picked up the first thing that her hand fell upon – a frying-pan – and emerged in the hallway just as Sherlock Holmes came through the door, throwing her into violent hysterics.

'I found myself in my old armchair in my own old room, and only wishing that I could have seen my old friend Watson in the other chair which he had so often adorned...'