"Adriane."

Sherlock's greeting is curt, formal, as I step into the lounge. John is at the desk and gives me a much warmer welcome. "Hi Adri, how are you? Cup of tea?"

I look at Sherlock, not sure whether tea was part of this evening's plan. He's on the sofa, parts of a dossier spread across the coffee table, focused on whatever it is he is studying. He looks gorgeous as always. Other than his verbal acknowledgement he has given no indication that he's registered my presence. I say yes, please, and follow John into the kitchen.

Maybe he has a better idea of why I'm here tonight, because so far this has been a strange one. Sherlock's text arrived three days ago telling me to be here on Friday and be rested. Other than that I have had no further communications. "Any idea why I'm here?"

John hesitates a moment before answering. "Ehm, yes, I do, but I'm sure Sherlock will explain. I'm not sure you'll be too impressed with this one, Adri."

Nothing new there, I think. So far none of Sherlock's experiments could have been classed as enjoyable, although there have been points of light in the weirdness and I have found out an awful lot about myself in the process, and still am. With a slight shudder I think back to a couple of weeks ago, to an electricity experiment where I learned that I really don't enjoy having parts of my body electrocuted regardless of how low the voltage and despite Sherlock's constant assurances that it was safe. "You're not telling me anything new, John."

He looks at me, concerned as usual. "Maybe. This one's different. Remember you can say no." After that he hands me my tea and changes the subject.

After ten minutes or so Sherlock wanders into the kitchen. "Ready for a night out?"

I give him a blank stare, then look back at John. This doesn't sound too bad. Most likely that is because I'm missing something, or maybe John was winding me up.

"Sherlock, tell Adriane what you're really planning." John sounds serious. Not a joke, then.

"I require you to accompany me on a case. John has regretfully declined."

I change my mind. This really doesn't sound good. Vaguely I ask, to the room in general, "Why?"

John snorts. "Because I refuse to dress up in black latex like some gay porn icon to spend the night at an S&M dive, regardless of how crucial it might be to solving a murder case."

The mental image takes a bit of getting over. "What?" I manage after a moment.

Sherlock sighs. "As usual you are over-simplifying the issue, John. Let me explain, Adriane."

He walks back to the living room and John and I follow. I'm very unsure about where all this is going.

Sherlock has seated himself on the sofa again and pulls a few photographs from the dossier. "You don't need to see all of it, but these will give you an indication what we're dealing with."

He passes the photographs to me. John just grunts and walks over to the sofa to sit down next to Sherlock. It's clear he's seen these before and has no wish to relive the experience. I look at the top photograph cautiously.

The first thing I notice is that there's a lot of blood. The next thing is the victim herself. It's hard to guess her age from the picture, but what stands out is the meticulous way in which she was bound in leather cuffs, rope and a ball gag before she was killed.

I've seen enough; the image makes me feel sick. I pass the photographs back to Sherlock, who briefly raises an eyebrow but doesn't comment. He puts the pictures back in the dossier.

"Elizabeth O'Connor, known as Lizzie to her friends, twenty-three, to all intents and purposes single. Brutally murdered about three months ago by an unknown perpetrator. Although the crime was made to look like a BDSM scene gone wrong, it wasn't. It was vicious, and it was premeditated. However it is clear that the killer knew his stuff."

I look down at Sherlock. "Three months?"

He sighs. "Yes. Initially the police thought they could deal with this one. She was a well-known figure on the local fetish scene, frequenting one club in particular. Unfortunately they barged in and started interrogating people left, right and centre. As you will be aware it is a community that looks after its own and has a healthy suspicion of the police. Not surprisingly they got nowhere."

John clears his throat. "Sherlock, they didn't really barge in as such. It was a covert operation. They tried to infiltrate."

"As covert as that lot will ever get," Sherlock says with derision. "All they did was waste a lot of time and get these people's back up. It's only made it harder to get near anyone."

He stands up and walks over to me. "I've done a lot of groundwork in the last few weeks. While I have managed to establish a presence and gain some trust there, I'm afraid I will not be able to break through completely unless I show myself to be an active member of the community." He pauses and looks at me intently. "For which I require a submissive partner. Given John's flat refusal, Adriane, the obvious choice is you."

I have to be honest, I kind of saw this coming in the last few minutes, but I'm extremely uncomfortable about the prospect. I don't do this stuff in public and never have done. I don't even strictly do this stuff in private anymore, unless you count forensic experimentation as a BDSM activity.

"Ehm…," I say. "I'm not –"

Sherlock steps closer, eyes fixed on me. He cuts in, his tone of voice ever so slightly sarcastic, "submissive?" He lets it hang a moment, then adds, quietly, "owned?"

Now I'm blushing. I really didn't want John to hear that. Quickly I say, "No. Brave enough." I'm hoping that Sherlock's comment will go unnoticed.

The room goes quiet. John is sitting on the sofa, eyes narrowed, looking at Sherlock and me. I feel like running out of the door, now, but I guess I wouldn't be back again. Instead I stay rooted to the spot wondering where this is going to go.

"Sherlock, you can't own somebody." John's words are quiet, but there is all the promise of a fight in them.

I close my eyes briefly, wishing I could vanish. When I open them again Sherlock is reaching over to my throat, touching the silver chain. "On the contrary, I find it is working quite well for me." He's looking amused, calm. I find it strangely comforting, his complete lack of self-consciousness. He meets my eyes for a moment. I'm sure he can tell I am dying of embarrassment.

"For your information," John says, openly angry now, "slavery was outlawed in the British Empire in the eighteen-thirties or thereabout. You're two-hundred years out of date."

Sherlock considers this only a moment. "And yet, all across the country, thousands of people willingly pass themselves over to others for general or specific use every day, John. For an hour. For the weekend. For a year. For a lifetime. Because it gives them something they need."

John shakes his head. "Nobody needs to be owned by anyone, Sherlock." I've noticed he is pointedly not looking at me, not drawing me into the discussion. I'm grateful, because I wouldn't know what to say. He adds, "You could just marry her."

Now Sherlock looks a bit taken aback. "Why would I marry her? I don't lo-"

"Sherlock!" John looks absolutely horrified. "Yes, fine, thank you. You don't have to say it." Then, to me, "Sorry, Adri."

I'm reeling. I don't know how we got into this discussion, but I want out. Mostly I'm trying not to look too upset.

John sighs, sits back and runs his hands through his hair. He looks up at Sherlock resigned. "So how does this work?"

"In the same way it always has," Sherlock says. "There is no change to the situation, John. I have access to Adriane's services as before. She is free to carry on her daily life as she chooses unless it affects me, in which case I want to know. The only difference is that Adriane is clear on where she stands and what I expect of her." When John clearly remains unconvinced, he adds, "John, it is a voluntary arrangement. It can be broken off by either party without consequences. Although it is highly unlikely it could be renegotiated."

John stares at Sherlock for a long time, looking for the exact meaning behind the words, trying to find the catch. Then he briefly glances at me and says, "You're both bonkers."

Sherlock gives him a dismissive smirk. "Maybe. I'll leave it to Adriane to explain what made me decide to go down this route if she hasn't already done so. But not right now." Then he looks at me. "Time to get changed."

I haven't quite caught up with what he's just said. The prospect of having to explain to John what happened with that woman has me panicking. Sherlock is not giving me time to think, however. As I look at him he points to his bedroom. "There are some things in there for you. Put them on please."

In a bit of a daze I walk through the kitchen to his room, only realising that I haven't actually agreed to any of this when I see the clothes that are spread out on the bed. There isn't an awful lot of material, and what there is is shiny and black. "PVC," Sherlock says from right behind me. I manage not to jump, but only just. "Not quite as laborious as latex."

I turn round, refusing to move any further into his room, and look up at him. "No. I'm not doing this." It really is a step, several steps, too far. I am no way prepared for this, I have no idea what he's planning or what is expected of me and I'm feeling way out of my depth.

Sherlock regards me a moment, head tilted back, entirely unperturbed. Then he says, quietly, "If I may remind you that I have a favour outstanding. I am calling it in for this case."

I remember the promise, at any time, for any purpose. It takes me a moment to get to grips with the inevitability of it. I briefly consider pleading with him, but one look at his face tells me that there is no point. I might as well try to reason with a stone wall. There really is no way out.

Something must have shown in my stance or my face, because he says, "Good. Now get changed." He turns me around by my shoulders and gives me a little push into the room.

It doesn't take long. The corset takes a bit of doing but Sherlock laces up the front for me. He seems to be enjoying himself; there's a glint in his eye that I can't really appreciate. When he's finished with the corset he leans over and whispers, "You should be thankful I didn't choose a cupless one. There were plenty of those to choose from."

I swear I've gone bright red all over. To hide my embarrassment I put on the non-existent thong and the lace top tights. Sherlock is just watching, thoroughly amused. I try to ignore him but it's impossible, and I am steadily getting angry. As I pull on the shiny black shoes I say, "I'm starting to think you're just doing this to embarrass me."

"No," he says calmly. "But I do find you current predicament entertaining. You are acting as if I am going to throw you to the wolves."

I look at him, not sure what he's getting at.

"Adriane, we are going for a night out. We are going to have a look around this place, have a drink and talk to a few people. I've already met them. My guess is you might like some of them. I can guarantee you that nobody will do anything inappropriate to you. You are quite safe."

I frown. "You're awfully sure about that. I'm practically dressed as a porn star."

"Hm," he says. "Not quite. You won't be the least dressed person there tonight by a very long way. Besides, you are at all times under my protection, which I intend to advertise."

He fishes something from his pocket. It's a black leather collar.

I stare at him in some awe as it strikes me again how very good he is at playing this game. Had that been on the bed with the outfit, I have no doubt I would have done a proper u-turn and walked out the door once and for all. Now he's turned the situation round in such a way that I actually want to wear the thing.

Sherlock crosses the room to fasten the collar around my neck. I'm lost for words for the moment, feeling totally outmanoeuvred. I wonder how many steps ahead he really is, what else I am going to do tonight which is already premeditated. Although there is comfort in letting it all go, I am still scared. I'm also trying to ignore my very definite arousal although Sherlock's very close proximity is making that hard.

"Done," he says, stepping back and looking me over. "You'll blend in."

I look at him, wondering what he's organised for himself. To be honest he looks stunning in his usual sharp suit, the black shirt really setting off his pale complexion, but it's not really what I'd expect anyone to wear to a fetish club. "And what are you going to wear?"

Sherlock just smiles. "I'm ready to go." When I scowl with the unfairness of it all he leans over and adds in a conspirational whisper, "Dom's prerogative." He catches my eye; I can tell he's absolutely loving this. It doesn't help with my mood or my arousal.

Before I can say anything else, he points towards the living room. "Go and show John."

It brings me back down to Earth with a bump. In the relative safety of Sherlock's bedroom this has been OK, but really it isn't some kinky game. I don't relish the thought of John seeing me dressed like this. However, it's clear there's no getting away from it. Unless he's gone out he will see me when we cross the lounge at some point anyway.

I swallow hard and make my way to the living room, taking a few wobbly steps as I get used to the heels on the new shoes. John is sitting at his desk but looks up as I come in. For a moment he just stares at me, then he blinks as his eyebrows make their way up his forehead. He opens his mouth but no sound comes out.

"It's not that bad, is it?" I'm not sure what to make of his reaction.

He closes his mouth and clears his throat nervously. "Ehm, no, no, it's not. You look, ehm… Yeah. And you're going out like that?"

It's funny, he can't stop staring at me. If I didn't know better I'd say he was blushing. I don't think I've ever had this effect on anyone and to be honest it's a little bit unnerving. "Apparently so," I say. Then I remember that I was wearing a waist-length jacket when I came over. If I go out like this I will be displaying myself to the world at large. I cover my mouth with my hand. "Shit."

"Language, Adriane." I hadn't noticed Sherlock had followed that close behind. I very nearly swear again.

I turn around to him. "Sherlock, I can't. I didn't bring…"

My sentence trails off as I notice he is carrying a leather jacket. My size, not his. He passes it to me with a wry smile. "So I anticipated."

I try it on. It's a beautiful thing, perfectly tailored and cut just above my knees. To any outside observer I could be wearing normal evening dress, as long as they don't notice the collar. I suspect it wasn't cheap.

"The jacket is yours," Sherlock says. "So is the rest of the outfit should you wish to keep any of it after this case. I very much doubt I will have use for it again."

I look at him, trying to think of something to say, trying to work out what it means. I briefly wonder if he is trying to bribe me, but quickly realise that if he was he would have started with the jacket, not waited until I had effectively caved in already. In any case it's not his style. I have to remind myself that this is Sherlock, and he probably really just saw it as a practical solution for an anticipated problem. The fact that the coat is quite easily the most desirable item in my entire wardrobe is neither here nor there to him. I decide to take it at face value. "Thank you. It's beautiful."

He gives me a nod. "Time to go."

John has recovered his composure by now and sees us out. As Sherlock walks past him he takes hold of his arm. "Sherlock."

Sherlock stops, regarding John calmly, saying nothing. John looks at him for a while before continuing, "Just look after her, OK?"

Sherlock stares at John for a long moment before answering. "I have every intention to."

John still holds his gaze before finally giving him a nod and turning to me. I hadn't realised I was holding my breath but I let it out now. "Take care, Adriane. Don't do anything you're not comfortable with."

I'll stay here then, I think, but I don't say it. Sherlock sighs audibly. "Thank you, John. I promise she'll come back in one piece."

There is a taxi waiting outside. Once more it is clear that this whole night out has been very well organised and it seems Sherlock isn't leaving anything to chance. It makes me worry about what he might expect of me.

During the ride he silently stares out of the window, seemingly oblivious to my presence. I can't help but fidget, too worried to settle. After a while he sighs and turns to me. "Spit it out, Adriane."

"Ehm." I'm not sure where to start. There are lots of things I am worried about, but a couple of them really stand out. "Ehm… Are you going to… I mean…" I look at the floor of the cab, not sure how to ask this. His steady gaze is unsettling me.

"If you mean am I going to do a public scene with you, the answer is no, I am not. Not tonight."

I breathe a sigh of relief, although the not tonight has me worried all over again. I didn't even realise that this was not a one-off.

I'm sure Sherlock can read my concern, but he doesn't elaborate. "Anything else?"

"Eh… What if there's somebody there that I know?"

Now he's looking at me with a slight smile. "In that case I guess you may have found a new friend."

He studies me a bit more. "You are far too worried about doing something that comes naturally to you, Adriane. There is no requirement on you to be anything but yourself tonight. If you are looking for any new rules, there are none because I don't see the need for them. I'm not going to make you call me sir or master because frankly I find it corny and those titles are overused by people that little deserve them. The only thing that you are not allowed to mention is that we are there on a case. And if there is any acting required it will be on my part, not yours."

His confidence is stunning. I wish I could share it.

As he is talking the cab slows to a halt. Since I have been far too preoccupied with my own worries while we were travelling I have no idea what part of London we are in, and I don't recognise the street when we get out. Sherlock strides off towards the door of an unassuming nightclub but I can't move quite that fast in these shoes and end up tottering after him, feeling – and no doubt looking – pretty miserable. When he realises I haven't kept up he stops.

As I catch up to him he gives me an appraising look and raises an eyebrow. "There are a fair few people in there who would give their right arm to be in your position tonight, Adriane," he says. "I'd like to see a bit of pride, please."

I look up at him and nod, but I don't think anything he's going to say to me is going to make me feel any more self-assured. He looks at me a moment longer and says, "And then there's this."

Before I know what is happening he has put his hand under my chin, leaned over and kissed me.

All my worries evaporate as he explodes into my mind. There simply isn't space for anything else as he kisses me slowly, unhurriedly, managing to convey meaning where in the back of my mind I know there is none. It doesn't matter, I am lost in the moment anyway. When he finally pulls away after what seems like an age my legs are decidedly unsteady and my breathing is all over the place.

I look up at him. "Sherlock, I lo…"

He shakes his head ever so slightly as he puts a finger to my lips. "Remember it's only a game."

I take a deep breath. "Then I love your games."

For a moment he studies me, his face serious. I have no idea what he's thinking. Then he says, "Come on."

We hand our coats in at the door. My head is still in a muddle and if I had considered it properly I would have felt self-conscious, but the lady at the cloakroom never even looks at my outfit. Sherlock leads the way into the club.

I'm not sure what I was expecting, but it isn't this. At first glance the place looks like an ordinary night club, busy, with people at the bar chatting in pairs or groups, having a good time. There is music but it's not overbearing and I notice there isn't a dance floor. Instead, dotted around the room are some pieces of equipment – a St Andrew's cross, some benches and what looks like a rack against one of the walls. A lady in a very tight latex outfit is strapping someone of whom I can only see the back to the St. Andrew's cross. The person in question is wearing nothing but a collar.

But the thing that catches my eye most are the clubbers. If I was expecting a group of the Beautiful People I couldn't have been more mistaken. It is a mixture of old and young, tall and short, fat and thin and everything in between. There are quite a few people not wearing very much at all, but nobody is staring and no one seems to be in the slightest bit body conscious. There are also quite a few people that are fully dressed, although most of those outfits leave little to the imagination. Some of the hair and makeup is outrageous. A few of the people look decidedly scary, but most of them frankly don't.

I realise that I am staring when Sherlock comes back to me. "Adriane, I expect you to follow me, not ogle the clientele."

I come out of my reverie. "Sorry," I say vaguely.

He's just staring at me, one eyebrow raised. I realise I've missed something. It doesn't take much thought to work out that although there may not be any new rules that didn't mean no rules at all and he is going to stand on proper protocol tonight. I can feel myself going red. "I'm sorry, Sherlock."

He nods. "Quite so," and walks off. I follow him in a bit of a daze.

As we walk to the bar a young girl with bright pink hair detaches herself from a group of people and practically bounces over to us. She's dressed in an elaborate red and black lace corset that clashes spectacularly with her hair, a pair of black fishnet tights and some shiny boots with heels that I could never even contemplate wearing. She's wearing a shiny pink collar with a little sparkly heart on it. When she gets to us she gives Sherlock the most radiant smile. "Hello, gorgeous."

"Jennifer." Sherlock's greeting is courteous, reserved.

The girl either doesn't notice or doesn't care. She rolls her eyes. "It's Jen, Sherlock. You know that by now. And who's this?" She looks at me curiously.

"This is Adriane. Adriane, this is Jennifer."

The girl giggles. "Hi Adriane. I guess that's Adri, then? Does he ever shorten yours? He's so formal, isn't he. Only my mum calls me Jennifer."

I have to admit, she's a bit much to take in, but she seems very nice. I smile at her. "Yeah. Most people call me Adri."

"You know I thought you were making her up, Sherlock. She's gorgeous. Some of the girls are going to be sorely disappointed. Andy's at the back, by the way." She flashes us another big grin, spontaneously kisses Sherlock on the cheek and bounces off.

I have to laugh. "She likes you."

Sherlock rolls his eyes and sighs. "Yes. The youthful exuberance of a happily collared submissive. I will need to have a word with Andrew."

We make our way past the bar, to an area somewhat out of the way. There in a corner are a few leather sofas and an old glass coffee table sitting amongst a pile of scatter cushions on the floor. A few people have made themselves comfortable, some on the sofas, some on the floor. Sherlock approaches them as if he owns the place.

As we get to the group a young man looks up. He's wearing very tight leather trousers and a half-open black shirt, but other than that he looks unassuming. "Sherlock. I was wondering if you'd turn up tonight."

"Andrew, I believe you may need to see to your submissive. She kissed me."

The young man grins. "On the cheek I hope. Talk to me again when she starts using her tongue."

The people on the sofas laugh and Sherlock smiles. He sits down next to Andrew, giving me a nearly imperceptible nod to follow suit. Without knowing what else to do I sit down on a couple of the cushions in front of the sofa next to him, figuring that literally keeping a low profile is the best way to draw as little attention to myself as possible. A couple of the people eye me up curiously but Sherlock doesn't see fit to make introductions, and I'm not sure of anything so I keep my mouth shut.

Sherlock enters into a quiet conversation with Andrew, which gives me some time to look around the group. Apart from Andrew there's a middle-aged lady dressed in all leather and buckles, with a pair of thigh-length boots which scream Domme. She's talking to a young man about half her age who is sitting on the floor, looking up at her adoringly. I can't think anything other than that they look rather sweet. Next to them are two men dressed in a lot of very tight latex, deep in quiet conversation. The way their legs are entwined makes it clear they are a couple, but it is not immediately obvious who the dominant partner is.

Before I have a chance to study anyone else a man in his thirties who seems to be mainly made of blonde curls and tattoos joins the group. He sits down in a solitary armchair at the head of the group and everyone says hello. He greets everyone briefly by name. When he gets to Sherlock he gives me a quick glance over first. I get the distinct impression he's weighing me up.

"Sherlock. Who's your friend?"

"Dominic." Sherlock is as ever formal, a little cautious maybe. It makes me sit up and take note even more than I already was. "I brought Adriane. Adriane, this is Dominic. He runs this little venture."

I say hi. The man returns me a wide smile. "Most people call me Dom. It's easier to remember."

I smile back, not sure what to say. Here is someone who it would be very silly to judge by appearance, is all I can think. However the conversation resumes almost immediately, leaving me to my thoughts once more. Jen bounces over after a few minutes and gives me a radiant smile, then hops onto the sofa and snuggles into Andrew.

My eyes wander to the last member of the little group, a young man on his own who meets my eyes with a face that is full of disdain.

"Hey, detective boy. Your undercover police woman is staring at me."

The group instantly goes quiet. I fight a sudden urge to grab onto Sherlock's leg for a bit of moral support. To my surprise he makes the contact himself, subtly shifting his position on the sofa so that his lower leg is now pressing lightly along the entire length of my back. I lean into him a little, worried about what's going to happen. I find it hard to believe he's done something as stupid as using his real name here, allowing everyone to find him on the web as easily as I did.

Sherlock lets the silence hang a while, the air thick with tension. Then he says, "As I have explained to you before, Kelvin, I am not here on a case. Do you really think I would use my real name if I were? It is the easiest thing in the world to assume an alias in a place like this. You prove that every time we meet."

There is a clear challenge there, although it is delivered quietly. Instead of taking Sherlock on the man turns to me. "Yeah, he's right. It's because I'm hot, baby."

I just stare at him, totally tensed up now. I'd like to run away.

Behind me Sherlock is moving. When I look up to see what he's doing he is putting his wallet back in his inside pocket. Then he passes me a ten pound note, his gaze steadily fixed on the man across from him. "Adriane, go and have a drink with Jennifer. No alcohol. I will see you shortly."

Jen is quicker than me. She's on her feet and holding out her hand before I have even begun to move, tension making me clumsy. She pulls me up and we make our way towards the bar quickly. As soon as we are out of earshot she says, "Wow. Kelvin is way out of line. I'm sorry, Adri."

I look back and she follows my gaze. Sherlock is still sitting motionless, maybe waiting for us to get well away. "What do you think he's going to do?"

"Not sure," I say. If I'm being honest I don't feel an ounce of sympathy for Kelvin, but I'm worried that Sherlock may blow the whole case if he shreds him. On the other hand I realise that I have no idea what game he is playing anyway, being so public about his profession.

We get to the bar and I order drinks. "Do you think they'll have a fight?" Jen is persistent, looking worried.

"No, I don't think so," I answer. "It's not his style. Unless Kelvin goes for him, I suppose." We are both looking across to the group, trying to gauge what is going on. Sherlock hasn't moved position, still fixing Kelvin with his stare, but he's talking now. The other man is looking perplexed, his mouth hanging slightly open.

Jen giggles. "Kelvin looks as if someone's slapped him."

I smile. "Sherlock does tend to have that effect on people when he gets going."

When Sherlock finishes talking Dom gets up and walks over. He gets to us and gives me an evaluating look. I don't know what he's searching for, but it makes me feel uncomfortable. "Well," he says. "That was impressive."

I give him an awkward look. "What happened?"

"He pretty much took Kelvin apart. I'm not sure how he knew half the stuff he did." He stops and looks at me again. "He's very protective of you."

"Oh," I say. I didn't realise the conversation had been about me as well. "What did he say?"

Dom gives me a slight smile. "I'm sure if he wanted you to know he'd have let you stay."

I feel myself blush, and give myself a reminder that he runs this place, he's bound to be good at the power games. Suddenly I'm not so sure how much I'm supposed to say to him. While I'm fretting I look over to Sherlock, who very briefly meets my eyes and gives me another tiny nod. I'll take that as permission to speak freely, then, I think. It seems things at the sofas have gone back to normal again, although Kelvin appears to be sulking.

Jen is pouting. "I would have liked to have heard that. How unfair."

"It wasn't pretty, Jen. He's sharp, isn't he, Adri."

It's a statement, not a question. All I can think is you have no idea. "Yes," I say. "Very."

"Has he ever done that to you? Take you apart like that?"

It's my turn to smile now. "He does it regularly. It's a special skill of his."

Dom is looking at me again, eyes narrowed, trying to work me out. I get the feeling there is a lot more hanging on this conversation than I thought at first. "And you are OK with this? Most people I know would run a mile. Kelvin is going to take days to recover by the looks of it."

I look back at him, wondering what he's trying to get at. I guess he's wondering whether I'm real, or whether I really am some undercover constable. I decide the honest truth is probably the best. "Sherlock understands me at a level that nobody else ever has. There is a lot of freedom in being with someone like that even if it's painful at times. In any case he usually has a good enough reason for doing it."

"Do you live with him?"

I'm not sure it's an appropriate question. Jen is frowning and I take it she thinks so too. I answer it anyway. "No. I don't think I could. He never switches off."

Dom has another good look at me before nodding and moving off. It's left me a bit shaky but thankfully Jen turns it round immediately. "Jeez. What was all that about? Everyone's gone mad."

She drags me to the bar and gets another round of drinks. "Come on, let's go back."

We both turn around but before we can move we practically bump into Sherlock who must have come up behind us quietly. Jen startles with a "Waah" and lets go of her drink as she puts her hands to her face. Sherlock catches the glass in a flash before it hits the floor. There is barely a spill.

"Jennifer." He gives her an elegant little bow as he passes her drink back. Jen just does the big eyes at him, momentarily speechless. Sherlock looks at her intently and smiles at her, a knowing little smile, and she goes a beautiful shade of scarlet. With a little wave of her hand in front of her face she says "fuck," giggles and quickly walks back to the breakout area where she throws herself onto the sofa next to Andrew.

"I think you made an impression," I say to Sherlock. He just nods, "Hm." Then he looks at me a moment, assessing me for something. "Coming back?"

When we get to the sofas everyone apart from Andrew and Jen has gone. Sherlock sits down across from them and I go back where I was, on the floor next to him, out of the line of fire.

"Adri, you're allowed on the sofas you know." Jen is looking at me somewhat scandalised. When I say I'm happy where I am, thank you, she climbs down from where she is and settles on the floor herself, between Andrew's legs.

She chats at me about everything and nothing. It's hard to keep up with her constant changes of subject, but it makes her easy company. I don't have to say very much at all. After a while she starts on a series of anecdotes about events at the club, drawing some giggles from Andrew when she retells stories of scenes that didn't go quite as expected, submissives stuck in awkward situations, dominants getting things spectacularly wrong. Sherlock and Andrew have stopped talking to listen to her as the stories become more and more outrageous. After a particularly saucy tale there is a moment of silence.

"Are you going to give us a demonstration tonight then, Sherlock?" Andrew's tone of voice is fairly neutral, but there is no mistaking the curiosity in his eyes.

Sherlock considers him a moment, then looks at his watch. "No. I have a private room booked in five minutes."

I try to hide my considerable shock, not very successfully I think. Jen is grinning at me. "Didn't see that coming, then?"

"Eh, no," I manage. I'm glad I can't see Sherlock at the moment. Just imagining his smug expression is more than enough. I'm aware I'm blushing again.

"And with that," he says, amusement all too clear in his voice, "I'm afraid we must leave you for the moment."

He gets up and I scramble to my feet, composure completely gone. "Breathe, Adriane," he says quietly as he lightly takes my hand and leads me away. I look back over my shoulder to Jen, who gives me a cheerful wink. Andrew is grinning.

We move through the crowd that has now started to form in the main room. I am vaguely aware that there are a few public scenes in progress as we pass by, but to be honest I am far too preoccupied with what Sherlock is planning to take much notice. He's let go of my hand and is weaving through the people confidently, leaving me to try and keep up with him.

The private room isn't very big but it has plenty of equipment in it. The first thing Sherlock does is a detailed sweep of the place, examining the walls with great care, occasionally clambering onto the furniture to get higher up. I'm watching him with some confusion, wondering what on Earth he's up to. When he's finally satisfied with the results of his search he hops down from the spanking bench he's standing on and says, "No cameras. Good."

I hadn't even considered that. The idea of someone filming what goes on in these places adds a whole new layer to my apprehension. Sherlock walks over to an armchair positioned in a corner and sits down, long legs stretched in front of him, hands folded under his chin. He closes his eyes and appears to drift off.

I'm still standing in the middle of the room wondering what the plan is. When I haven't moved for five minutes or so Sherlock opens his eyes again and says, "Might as well make yourself comfortable. We will be here a while."

"Wha-…," I manage, then, "Oh." I'm completely thrown. As an afterthought I sit down on the spanking bench.

He's looking at me with amusement. "Adriane, we are merely here to keep up appearances. I'm not planning anything."

"Oh," I say. I'm not sure whether I sound relieved or not.

"If I didn't know better I'd say you were disappointed. Remember you were the one who didn't want to come here tonight," he says and closes his eyes again.

I look at him. He looks relaxed, at home, self-contained, gorgeous in his confident indifference. Looking around the room at the equipment, the rack of floggers, the neatly coiled rope hung in one corner, I can't help but wonder what he would do if he did decide to do a scene. I have no doubt it would be an experience not quickly forgotten. My eyes drift back to Sherlock as my thoughts wander into some fairly vivid fantasies. With a start I realise he's watching me.

"Really."

I close my eyes as I feel myself blush furiously. When I open them again he is smiling slightly, still watching me. "Adriane, you're altogether too predictable."

He gets up in a graceful movement and crosses the room to me. I feel the urge to bolt. Looking up at him I say, "I thought you took no interest." I'm aware it sounds like an attempt to deflect him.

His smile widens slightly. "Too late," he says quietly. "Get up."

I stand up, a bit wobbly, apprehension fighting it out with arousal. He stands back and considers me, then reaches over and very matter-of-factly begins to unlace the corset. "You are right in that I take no interest in sexual activities as they are by their very nature repetitive and limited in their scope. The mind games, however, are a different matter altogether."

His timing is impeccable. As he finishes the sentence the corset drops to the floor, tights and all, and I am left standing in a puddle of fabric wearing nothing but a collar and thong that covers about half a square inch of me. Sherlock motions for me to step out of the tights and shoes.

When I am done he moves in very close and looks down on me. I'm suddenly acutely aware of how much height I have lost when the shoes came off. "I also have no interest in all that stuff," he says, waving his hand at the equipment around us but keeping his eyes fixed on me. "While I am sure it has its use in certain situations, I have no need for it when all I require to get into your mind is this," he points to his head, "and this." He holds up his right hand and I just stare at it, wondering where this is going. Then he leans in very closely and whispers, "Which I will demonstrate."

I swallow hard. While arousal may be winning my nerves are jangling. I am familiar and relatively comfortable with Sherlock on a case, who is always factual and to the point. I am much less familiar or comfortable with Sherlock playing games, although he has shown me some of that side of him, and it has invariably left me an emotional wreck. But this is him showing off, for the sole reason that he can, without any cause that I can see other than that he has an hour or so to spare. Frankly, it terrifies me.

Sherlock is watching me, reading my reactions. "Maybe you should be more careful what you wish for, Adriane," he says quietly.

I look back at him. His total focus is positively overwhelming and I realise I'm being offered a rare opportunity even if it frightens me. I shake my head. "No."

Sherlock gives me a lopsided smile. "Good. You didn't have a choice, anyway."

Even if he just said it for effect the impact is impressive. I manage to stay upright but my legs have gone terribly wobbly. He hasn't even touched me and I'm already struggling to keep myself together. Sherlock takes off his jacket, then steps up close to me and lifts his hand again. "Don't move."

He moves his fingers within a hair's breadth of my chest and leaves them there a moment. I can feel the warmth radiating off his hand and am waiting for the contact, but it doesn't come. After a minute or so he moves his hand downwards and over my breast, then stops again just over my nipple, still not quite touching me. I have to resist an urge to push forward.

"The game," he says very quietly, "ends when I touch you."

I have to suppress a whimper. The way I am feeling this could be a very short-lived session.

He moves around the back of me. "Close your eyes."

If I thought that without being able to see him I wouldn't be aware of what he is doing I was mistaken. By now my skin is so sensitised that I am picking up every bit of warmth coming off his hand as he slowly traces it just above my body. He must be standing very close because on top of the warmth of his hand I can feel his body heat against my back, his breath ghosting over the hairs on my neck. I am desperate for him to touch me. It is taking a lot of effort to stay motionless and by now I am emitting a steady stream of small whimpers.

Occasionally he stops his hand above a particularly sensitive spot; along my hipbone crease, over my breast, at the small of my back, but never going any lower. When he moves back up over my breast towards my throat I find myself arching my head backwards, giving him fuller access. It elicits a low chuckle from Sherlock, far too close to my ear. "Good."

I give a small moan. This is slowly driving me mad. I desperately need him to touch me but I know that would be the end of it, and I don't want him to stop either. It's not enough and it's too much at the same time and it leaves me feeling impossibly, achingly aroused. My skin is physically burning and has become so sensitive that I can feel the slightest shift in the air when Sherlock moves, anticipate the steady trail of his hand, feel his breath even when he moves some way away from me. My whole body is trembling.

"Would you like me to stop?"

He's moved in front of me again and I open my eyes to look at him. He's studying me, impassive, the glint in his eye the only indication that he is enjoying this intensely. I find it hard to look at him without completely losing it, so I close my eyes again and shake my head. I swear I can feel his smile.

He continues, once more close to me, but there is a sudden shift in his position. It takes me a moment to work out that he has kneeled in front of me. The warmth of his hand is making its way down now, over my pubic mound, down the inside of my thigh, back up over my buttocks, round again slowly. Most enragingly his face is just in front of my belly and I can feel his breath warm on my skin, driving me to distraction. I'm not sure how much more of this I can take.

He begins to blow softly on my skin; it's as close to a touch as he's come tonight and I lean towards it, trying for more. Still there is no contact. I am moaning with frustration as he moves slowly down, his hand following suit, warmth and featherlight touch focusing very close to my sex.

Suddenly an intense sensation cuts through me, so strong it is very close to painful as he touches my clitoris through the non-existent thong. It takes a fraction of a second to realise that he isn't using his hand but his lips. Almost instantly I lose all control of my legs, my knees buckle and I sink to the floor. "Fuck."

When I open my eyes my face is inches away from Sherlock's. He smiles. "It appears I could even have done without the hand."

I have never been closer to just jumping him, consequences be damned. My need for release is overwhelming. With effort I restrain myself. "Sherlock, please."

"No," he says and stands up. "Time to go."

He holds out his hand and pulls me up off the floor. I end up far too close to him, legs still unsteady, fighting the impulse to snog him. "Hng. How can this not have an effect on you?"

He eyes me up, amused, then goes and picks the corset off the floor. As he is calmly lacing it back up for me he says, "it's called self-control, Adriane." With him that close to me again I'm having far too much trouble keeping my thoughts straight to be able to even comment on that. I notice he is still very careful to avoid any skin contact. "Besides, as I said, I don't take much of an interest. And having you in a state like this is much more entertaining."

He straightens up, gives me a final innocent smile and motions to the door. "After you." I'm caught between the impulse to hit him or to snog him. Knowing that an attempt at either is bound to be futile I scowl and walk out.

We make our way back through the club. My legs are still wobbly, I have no co-ordination and am finding it hard to focus. As a result I am staggering around the place trying to follow Sherlock, bumping into people and finally nearly walking headfirst into a pillar. I am amazed at the speed in which Sherlock is back at my side, grabbing my elbow and steering me in the right direction.

When we finally get to the breakout area I sink into one of the sofas, make my way to a corner and curl up into a ball, drawing my knees up to my chin. I'm still in a muddle, not enough space in my head to talk to anyone, so I keep my eyes firmly fixed upon the floor. Sherlock sits down next to me, carefully keeping his distance so as not to touch.

I don't take any notice of the conversation that is going on around me. Jen and Andrew don't seem to be there. Sherlock is also keeping quiet, just listening, observing. I don't recognise any of the voices and it allows me to sink into my own world, although I am failing to find many coherent thoughts.

After some time my trance-like state is broken by the appearance of a happy face framed in bright pink hair in front of my eyes, sideways. "Good session then?"

I blink. It takes me a moment or two to come back to the here and now. "Eh, yes. Yes." I'm still having problems focusing.

Jen looks at me curiously, then at Sherlock. "What did you do, Sherlock? Must have been impressive."

He looks at her, a faint smile playing around his lips. Then he raises an eyebrow and says, casually, quietly, "I never even touched her."

Her eyes widen. She looks at me for confirmation and I give a half-hearted smirk. There isn't much point denying it, although this won't do anything to lessen Sherlock's self-esteem. Jen looks back at Sherlock with an expression of awe on her face. "Jesus."

He's fixing her with a steady smile as Jen's face turns bright red. I'm wondering what Andrew is making of all this, but when I look at him he's grinning. I guess he's feeding off it, maybe thinking of using it as a tease on her later. As I turn back towards Sherlock I swear he is passing Andrew a tiny wink.

Shortly after Andrew takes Jen off. As they disappear into the crowd Sherlock looks at his watch. "Time to go home, I think."

On our way out we come past Dom, talking to a small group of people at the bar. Sherlock stops. "Thank you for your hospitality tonight, Dominic."

Dom gives him a curious look before answering. "Coming again?"

"Yes. We'll be back next week. Adriane has rather enjoyed herself."

I wasn't ready to be drawn into this conversation and I also didn't realise we were returning quite so definitely. All I can do is stare at him. Sherlock returns my stare with a smug smile. It is obvious that he is playing some kind of long game here and that my sanity is the last thing on his agenda.

Dominic just grins. "Good." It looks for a moment as if he is going to say something else, but then he seems to change his mind. "See you next week." Sherlock nods and we leave.

The taxi ride back is a very quiet one and it seems to go quickly, although I am finding it hard to keep track of time with my head in a mess. I'm a little surprised when the cab draws up at 221B Baker Street, having fully expected Sherlock to drop me home. I really don't believe he would change his mind about sleeping with me so easily after what he has said tonight. When we get to the living room I find myself reduced to an awkward silence.

Sherlock has hung up his coat but I haven't even got that far. He comes over and appraises my confusion, then sighs and unbuttons my jacket for me. "You're staying, Adriane," he says as he peels it off. Then he adds, "I believe you owe John an explanation."