As clouds of dust began to separate their stolen Humvee from the pursuing tribesmen, Irene leaned back in her seat and caught her breath.

"I applaud your sense of timing, Mr Holmes."

Sherlock ignored her, intent on the potholed road ahead.

"I don't suppose you are going to tell me how you knew where I was - or what was happening to me? Not that I want to appear ungrateful, but ..."

"As ever, you focus on the wrong questions. You should be asking me how I knew that your taste in cosmetics has not changed in the last year - and the answer to that lies in the sentimentality of the rootless traveller seeking a scent of the familiar."

"You tracked me by my cosmetics orders? My perfume?"

"You were absurdly careless, Ms Adler. "Delight of the Lily" - a custom scent only made by one tiny perfumier in Oxford Street. Regular orders to a different hotel each month. Almost as if you wanted to be traced. When I discovered that someone in the compound of Abdul Hakro - the most dangerous man in Karachi and a noted confederate of a certain Moriarty - had developed a taste for this unique scent, I knew that you had got yourself into deeper trouble than even you could handle."

"Every girl has a weakness."

"And you have several."

The jeep veered off the narrow side-road and onto the main road to Karachi, the bright lights of the city looming up ahead like a carelessly heaped mound of jewels.

"So now what? We go our separate ways, without even a kiss goodbye? My noble knight of the mind, thankless and without reward?"

"Absurdly melodramatic. Spare me your poetry."

"Not even... dinner? My treat? I know a lovely little restaurant in Dubai."

"Dubai is nearly a thousand miles from here."

"I note you didn't say 'no'. If you turn left before the exit to the shrine up ahead, you will end up at a little private airfield. I know the owner of one of the planes there - or at least I know what he likes - and I'm certain he wouldn't mind us going for a little spin."

"Neither did I say 'yes'. A thousand miles for a midnight snack? Please. I'm not anxious to find out what little trick you have up your sleeve."

"Aren't you?"

They drove on in silence for a little while. Irene adjusted her lipstick in the rear-view mirror, and shrugged out of her enveloping robes to reveal a dress more "Paris" than "Pakistan".

"On the other hand, if you take the next international flight back to London, you should be back just in time for John to nag you about the milk. Any interesting cases at the moment? No? Of course not, or you wouldn't be here."

"Just dinner?"

"Just dinner."

Some time later, the small private jet levelled off on the runway of Dubai airport, rolling smoothly towards the waiting car.

"Excellent attention to detail."

"I do so hate hailing cabs at this time of night."

They stepped into the car and were whisked away from the airport along gleaming new highways built alongside towering malls and decrepit shanty towns.

Irene gazed out of the window. "I love Dubai. Such extreme affluence and suffering. In London, you can live a whole life without seeing true poverty. But here, it's so honest, so pure, so… cruel."

The car drew up at the foot of one of the gleaming skyscapers. Despite the lateness of the hour, partygoers buzzed in and out of the elaborate glass buildings. Chauffeurs and cab drivers dropped off wealthy-looking couples, locals in Arab dress, and foreign tourists, all mixed up in a promiscuous profusion of desert clothing, khaki shorts and designer dresses. A stiff-uniformed doorman guided them inside out of the blasting desert air into a cool mirrored lift; a vast kaleidoscope of mirrors and glass. Irene pressed a button for the highest floor.

At the top of the skyscraper, the doors slid open to reveal a hushed and new-looking restaurant, with exquisitely placed tablecloths and napkins, and a design that screamed "expensive." The waiter ushered them to a quiet table next to a broad window, with a spectacular view of the twinkling lights of the city below. Irene slid into her seat and studied the menu intently. Sherlock stood gazing out of the window, his arms behind his back.

"So why are we here? To impress me with your taste? Because, frankly, this place has all the élan of a Christmas tree in a Blackpool house of ill repute."

"Taste is overrated, don't you think? This place is just so deliciously over-the-top. I adore it. Sit down, won't you? I recommend the oysters."

"I rather expect you would."

He turned away from the window, and sprawled louchely on the velveteen chair, strategically facing the exits.

"So there you've got me. Dinner. Is is everything you thought it would be? Was it good for you?"

"I rather think we've hardly got beyond the foreplay."

"Tell me, are you still Moriarty's messenger girl? Or have you found a better sugar daddy?"

"If I was still working for Moriarty, do you think he would be trying to kill me?"

"Probably. It seems to be his way of saying 'hello'."

The waiter appeared almost silently. "For the lady?"

"The mesclun salad, please. And a bottle of champagne. Clos du Mesnil 1995. Two glasses."

"Sir?"

"Mineral water. In a bottle. A sealed bottle."

The waiter raised an eyebrow, and swept away.

"Paranoia doesn't become you. If I wanted to poison you, I wouldn't be so obvious about it."

"No doubt, but why make it easy?"

There was a pause. Irene picked up a spoon and twirled it in her fingers, regarding Sherlock with a steady gaze. Sherlock returned her gaze blandly.

"So how does a nice New Jersey girl end up in a place like this?"

"I see you've been 'researching' me. Well done. I thought I'd covered up my traces quite well."

"Love the accent by the way. Quite convincing."

"I trained for the stage. But the rewards are so poor compared the the line of work I ended up in."

"Such a cliché really. Good upbringing, Catholic school, overbearing father, absent mother, life off the rails."

"I'm flattered to receive such attention. I didn't know you cared."

"So what turned you away from the path of righteousness and apple pie?"

"Does there need to be a reason? I didn't want to live out my span as some two-hundred pound housewife wasting away in Essex Fells; the PTA meeting the highlight of my miserable existence. I left the first chance I got. Never looked back. Never will."

"Not even when facing an execution squad in the most dismal backwaters of Pakistan?"

"Especially then. I don't wish to sound ungrateful for the rescue, but when my time comes, I want to face it on my feet, spitting in the eye of Death, and not dribbling out my last in some foul nursing home, teeth in a glass beside the bed, relatives praying for my death so they can sell my jewels."

"Admirable sentiment. Of course, there's no danger of that, is there? I doubt any of your relatives know you are still alive."

"By my design. I have a sweet little grave in Passaic County. I lay flowers there every year."

"At least someone loves you."

"And how about you? Public schoolboy, Oxbridge education, trust fund. Shouldn't you be on the Tory Front Bench by now? Or at least in the City, screwing the economy out of every last penny, screwing expensive call girls in expensive hotel rooms? How did you end up a private detective, so broke you need to share a flat with an unemployed army doctor? How does Mummy feel about that?"

"I see you've done your research too. But I can hardly congratulate you. I've not exactly covered up my trail."

"Oh, I know more than that. I know why you were thrown out of Cambridge. I know about Vic Trevor and his little dog. How... humiliating that must have been for you."

Sherlock looked annoyed. "And how do you know that?"

"I talked to your former tutor. Well... more than talked, really. He was very forthcoming. You weren't exactly Mr Popularity in Uni, were you? I'm surprised you lasted as long as you did."

"My peers were tedious idiots, passing time by drinking heavily while waiting for Daddy to hand out the plum jobs, and passing exams by paying the state school kids to write their papers. I'd have shot myself from despair if I'd spent one minute trying to gain their worthless approval."

"As I recall, you did shoot someone, didn't you? Wasn't that the entire problem? Lucky Mycroft was already in the Secret Service by then, and hushed it up so effectively, or you might have gone to prison. Especially with those inconvenient drug test reports."

"Why should I justify myself to a failed opera singer who makes a living by extracting cash at whip-point from a succession of chinless morons?"

"You might consider what might happen if your adoring press ever decides to do a modicum of actual research on your life story."

"Oh, blackmail. Boring. I wondered what the point of this little escapade was. How disappointing. I expected something a little more original."

"Oh, don't worry. You have nothing to fear - from me at least."

The waiter returned with a silver tray, and discretely laid out the food and drinks, pouring a glass of champagne for each of them. Irene sipped delicately from her glass. Sherlock ignored his, and the water too, leaning back in his chair and aiming a piercing gaze at Irene.

"So now we've got to the point of this meeting, is there a reason to continue? Or can we call it a night? I told John I was going to the British Library to research the life-cycle of the honey bee, and even his unremarkable mind might think it odd that I've been gone three days."

"You think that's the aim of this tête-à-tête? I have much lower designs than that."

"You're going to try and get me into bed? I must admit, you have a very odd idea of seduction. Perhaps it works on your clients, but you've already tried it on me. Several times. Without success."

"I like a challenge. Usually men are … so easy. It's tedious. Flash a nipple and they follow like a hungry dog after a steak."

"So you think I'm 'playing hard to get'? Perhaps it might occur to you that I'm not interested. Most people waste a lifetime chasing after validation from the opposite sex, and what does it get them? A house full of screaming brats and broken dreams, with two people who can barely disguise their loathing for each other going through the motions for decades until merciful death releases them."

"Yes, I've heard about your parents' marriage. But I'm not offering a relationship. How tedious would that be? Just one night. Aren't you tempted? Have you never wondered what the attraction is?"

"Frankly, no."

"You've never been with a woman have you? No, don't deny it. My research turned up nothing, and believe me, I can always discover something of that nature. It's a professional asset."

"So what's it all about then? The challenge of unknown territory?"

"Partly, perhaps. I'll let you into a secret that could destroy my professional reputation. I've never been with a man. A good dominatrix never sleeps with her clients. It destroys the illusion of power. And my recreational tastes are usually with the distaff side."

"So you're the only virgin whore in England then? This gets better and better. What a lovemaking for the ages that would be. I must confess I lost the little informational pamphlet they gave us in Prep School, but perhaps you remember the details?"

"Oh, I rather think I'm quite familiar with the theory."

"So I've managed to convert a lesbian then? Entirely by accident. You'll have to tell me what I did, John tries so hard but never succeeds. I could give him a few tips. Perhaps there's hope for him and Clara after all."

"Interesting your mind goes to John. Do you think he would disapprove?"

Sherlock stared at her. She smiled, and played with her salad.

"It seems I've offended you. Many apologies. Perhaps we can still be friends?"

"Were we ever?"

"I think we had a connection."

"You were a case, nothing more."

Irene drained her glass, and poured another. Sherlock's lay untouched, along with his water.

"I pride myself in always knowing what a man likes. And I think I know what you like."

"Oh? I think you've conclusively proved that you don't."

"That was just teasing."

Irene produced a small green leather case from her bag, and opened it up. Inside was a sachet of white powder and a silver straw. She tapped out a little of the powder on the polished table. Sherlock raised an eyebrow.

"Oh, don't worry. I know the owner of this restaurant very... well. They won't make a peep."

"A shame, because getting arrested on drug charges in Dubai has always been a particular ambition of mine. I just want to see the look on Lestrade's face."

"Go ahead. Or are you still 'in recovery'?"

"Technically. You first."

"Of course." Irene delicately hoovered up a little of the powder. "Not the best in the world, but the highest quality I could get at short notice."

Sherlock snorted some of the cocaine. "Pleased now?"

"Quite."

"It seems you value your role as a temptress."

"I hope I excel at it."

"So what's the aim of all this? Incriminating photographs? Or do you think that one line will send me on some self-destructive downward spiral - because if so, I presume you've been talking to my brother."

"What do you think I'm trying to do? You're the detective, after all."

Sherlock paused, and frowned. "Information. You researched me, and now you're confirming your findings. For sale, or for personal interest?"

"I like to know where I stand. I like to know what makes a person tick. We're more alike than you think. You like to solve mysteries. I like to solve people. I like to look into their deepest, darkest corners. The things they'd never tell anyone. The links they tried to clean from their internet history. The thing that makes them break. There's always something."

"You should talk to Mrs Hudson, if you think that's true. I'll tell you her darkest secret for free. She once confided in me that she substituted marge for butter in the cakes for the church fair."

"Very amusing."

"But I'll tell you what makes you tick. You're empty. Nothing inside. You try to manipulate people to make you feel like you exist, and you try to control people through sex and pleasure and pain because it's easy. But when there's no-one around, no-one to manipulate, do you even exist?"

She smiled, wryly. "Perhaps it's true, in a sense. The world's a game, and most people are pawns. The players are those that know how to move them around. The winners are those who know how to break the rules."

"You're a piece that thinks it's a player. Moriarty moves you around the board and you don't even notice. I'd feel sorry for you, but I still have enough regard for you to refrain from the insult."

"You could have real power, but you'd rather amuse yourself finding lost cats and wives, or acting as a guide-dog for the London police. You could be a player, but you are bound by a pitiful respect for the rules."

Sherlock smirked. "I don't break the rules. I make the rules."

"From what I hear on the grapevine, we'll all find out whether that's true, and sooner rather than later. But I'm getting restless. Walk with me." Irene got up. "Don't worry about the bill. They won't charge me here."

"Because you know what the owner likes - yes, I get it."

Outside, the early morning was tinged with gold on the dark horizon. The hot streets of the city were still inhabited by the straggling last few partygoers. The street-sweepers were just starting to clear up the remnants of the night's excess.

They wandered through the streets until they found themselves on a low bridge over a broad river, and watched the water lapping at the pillars for a moment.

Irene looked philosophical. "I wonder... could it ever have worked out? Was there ever hope for us?"

"Never. And you never wanted it, either."

She sighed, and turned to walk away. "Good-night, Mr Sherlock Holmes."