I think it is not an exaggeration to say that Operation Songbird is the most fraught week of my professional life since joining the Service, for reasons I could never have foreseen when I first applied, all those years ago. If I had been told, last year or even last month, that one day I would be working directly against the will of Her Majesty's elected Government, I would have laughed outright at such an unthinkable notion, and yet, that is exactly what I find myself doing, from the very first day of this operation. I still can't quite believe it, as I sit in the surveillance van outside the Excelsior Hotel: at any moment I expect SO19 to come crashing through the doors of the big white vehicle to take us all away to the Tower through Traitors' Gate. Harry's final briefing to us had warned of the likelihood of "extreme unpleasantness" coming our way, should we fail in our aim, even though off the record, the operation had been sanctioned by Juliet Shaw, our chimerical National Security Coordinator. I had taken this highly unsettling statement to mean that she wouldn't hesitate to leave us twisting in the wind, and step back smugly into the shadows of Whitehall, should the operation be exposed.

Total secrecy is imperative, even though the media is beginning to break the story of a financial crisis in the NHS, thanks to a rather torrid session of Q&A in the House Select Committee on Health by Malcolm Stackley, MP, our erstwhile canary in the coalmine, which had initially piqued their interest. It's part of the plan, of course – the fourth estate may well think of itself as free, but we all know that nothing is really as it appears, when it comes to the news. For myself, I gave up watching it more than a decade ago, tired of the discrepancies between what I knew and what the media was purporting to be the truth, but I do still take The Times for the crosswords and the literary supplement. One has to make some sort of effort to stay abreast of social and cultural developments, after all, and to that end I also take The Guardian, just to see what the other half is saying. Besides, Mother likes the paper, of a morning, for the lifestyle and society pages.

Even while focused on the bank of monitors before me, all showing different aspects of the grand old hotel that Korsakov calls home in London, I still can't help but flinch at the memory of Mother at six this morning, descending the stairs in her peach finery, the dreadful green goop thankfully rinsed off, to be replaced with some sort of serum that made the skin of her face look tight and unnaturally shiny. She had come into the kitchen where I was already dressed for work, peaceably eating a piece of toast with marmalade and having a quiet read of the paper propped up against the teapot, and had immediately started kicking up a fuss about "that's not a proper breakfast" and "no wonder I was looking peaky." I had finished my toast, sculled down my still very hot tea, tucked The Times under one arm, and risen from the table before she could start wielding frying-pans and porridge-pots on my behalf.

Next, she had followed me out into the hall, scolding as if I was still thirteen. "Malcolm! That's not enough to keep body and soul together. You'll be hungry before morning break, and then I suppose you'll go and get a nasty greasy bacon roll from one of those dreadful, dirty cafeterias. Why don't I make you a nice poached egg with a little bit of smoked salmon… or there's kippers, if you'd prefer? At least have some porridge, I'm about to make some for myself. It's been soaking all night, see, it won't take five minutes… and you could do with a good breakfast, you've grown very thin since I was away. When's your annual medical? It must be due soon!" I had let her talk at me while I wound my scarf around my throat, shrugged into my overcoat, collected my keys and walked towards the front door. "Sorry, Mother, but I really do have to be in early today. In fact, I might be working some very odd hours for the next few days, so please don't worry about me, I'll fend for myself. And as for the annual physical review, some bright spark in HR has decided to spring it on people at random, instead of scheduling it, because they feel that too many officers are cheating – cleaning up their act for a few weeks before the medical, then going back to their wicked ways. All I know is that it is likely to be sometime this month."

She had looked at me in exasperation and said, hands on her hips, "Well, you've never cheated on anything, you'd think they'd know that after all this time. I can't imagine the asthma attack you'd have if you did! And you've also never fended for yourself in the kitchen in your life, my lad, and you know it. I suppose I'd better make a few things that will reheat nicely, then. I'll go across to Sainsbury's this morning; did you want anything in particular?" I had smiled as I opened the door, and replied, "I do fancy a bit of roast beef, if you think you could manage it?" Mother had shooed me into the portico indignantly. "'If you think you could manage it?' Really, Malcolm, who do you think I am? I've made more roast dinners than you've had hot meals, of course I can manage it, and a pudding too." "Jam roly poly?" l had asked hopefully, and she had snorted, "Yes, AND with proper custard. Now go on, or you'll be late! You don't want to keep Mr Pearce waiting, now do you?"

I had resisted the temptation to roll my eyes at this, and had instead dropped a swift kiss onto her cheek. With a final sniff, she had waved me off, before pulling her flimsy satin robe around her with a shiver and going back inside as I had walked round to the garage. While the car was warming up, I had pondered her last two questions, and had been more than a little perturbed to find that the answers seemed to be, Actually, I'm not quite sure at the moment, and Yes; I would gladly keep Harry waiting, if it meant that I could stop myself from setting foot on what every instinct for self-preservation is warning me could well be a fatally slippery slope. Thus preoccupied, I had turned the Rover towards Thames House, my heart full of foreboding and anxiety; luckily, the earliness of the hour had meant that I met with little traffic on the road, and so was saved from absent-mindedly drifting into the back of some unsuspecting motorist, or accidentally running over any small children, dogs or little old ladies on the zebra crossings. A large part of the foreboding and anxiety, of course, was devoted to Ruth, and to worrying about what has become of us.

I adjust the resolution on one of the cameras, seeking a sharper image of the interior of Korsakov's penthouse, but my thoughts cannot be distracted for long... After the night that Ruth had asked for a lift and I had regretfully refused, she had turned distinctly cool towards me, even at work. She avoided talking to me unless absolutely necessary, she ignored my comings and goings on the Grid, and had even actually pretended not to hear when I offered to make us all tea, earlier today. She had had the phone to her ear, but I could see that the little red light that meant her extension was in use wasn't on, and confused and hurt, I had beaten a hasty retreat to the tea room. Jo had followed me in, and offered to help. Lovely, kind Jo, so young, but already turning into a fine field officer, and one with a good heart, at that. "Are you OK, Malcolm?" she had asked, setting out everyone's mugs. "Oh, yes, I'm always alright, thank you," I had replied, not very convincingly, and she had looked at me in solicitude. "Did you want to try that again?" I had concentrated on pouring boiling water into each mug, now adorned with a tea bag tag wrapped around the handle by Jo. "It's just that you and Ruth are usually such good…friends…" she had begun, carefully spooning sugars - three for Colin, none for Ruth, and one each for herself and me – into tea, and removing teabags. I had said nothing as I reached for the fridge and extracted the milk, before wielding it over the four mugs. A lot, some, a dash, and a bit more, I reminded myself, as Jo went on, "Look, I know it's none of my business, but whatever's going on between the two of you, I hope you get it sorted, that's all. I'm beginning to realise that friends – good friends, proper friends – are few and far between in this business, and even more so since…since…Fiona…" and she had said no more, but had rubbed her eyes with the back of one hand like a little girl who has hurt herself, but is determined not to let on.

My heart had gone out to her, and forgetting myself, I had reached out to touch her on the arm in sympathy: to my amazement, she had moved towards me and before I knew what was happening, she was resting her forehead against my shoulder, staring down at the floor as she whispered to her feet, "I felt so alone, so helpless, standing outside that place while she went inside…I should have done something, I should have been there for her. I don't even know why I'm still in this job." Oh! she feels guilty too, I had realised with shock, and then I did something I have never done with any other field officer with whom I have worked: I put an arm around her slender shoulders, and drew her gently into a one-armed, sideways sort of hug: a friendly gesture, nothing more than a show of support, was what I had intended, but Jo had given one choked sob, before burying her face in my shirt-front, to my complete and utter astonishment.

Sighing resignedly – I seem destined to be sought out by female colleagues for a bit of non-threatening comfort – I had embraced her properly, then, recognising her need for comfort and reassurance in face of such harsh reality. Dimly, I noted that I wasn't trembling as I would normally, and despite Harry's thinly veiled warning regarding my future in the Service, I had thought of nothing except helping a fellow human soul in turmoil. It's at times like this that I wonder if I ought to have followed my father into the church… at any rate, we had stood there like that while Jo had gotten herself back under control. As I held her, I said softly, "Believe me, it's not your fault. I felt terribly guilty too, until I realised that Fiona had known exactly what she was doing." At that she had pulled away to look at me, eyes wide with surprise. "You? But, but, you NEVER do anything wrong!" I had chuckled sadly, "Oh, I would that were the case. I'm afraid that I'm only human, though, like the rest of us. I thank you for the vote of confidence, though, and I hope that you won't make any hasty decisions…we need you here!" and at that, she had shot a most Jo-like grin at me as she had stepped back. "C'mon, we'd better get this tea back to them," she had said, when from the doorway had come a low-pitched, cool voice that made us both jump. "Don't bother with mine," Ruth had said, and turned sharply on her heel before either of us could say anything. Jo had stared after her, and then said, "Bugger! Don't worry, I'll talk to her." Good luck with that, I had thought hollowly, collecting a mug in each hand and walking back to the Grid like a man going to his execution, while Jo poured the tea in Ruth's mug away with a shrug that said, Her loss.

Fortunately, she wasn't there when I arrived; Colin had looked up from behind his array and said, "She wanted me to tell you that she was going out for a meeting; she seemed in a bit of a rush." He flushed slightly as I had set his second-favourite Red Dwarf mug down, and I could see the distaste in his eyes at having been made to do her dirty work, so to speak. I had nodded with disinterest, before settling down behind my monitor to finish reviewing the audio recording captured from the bug in Hugo Ross's home, on the first night of his release – another little job that Adam had asked me to do recently. I had deliberately acknowledged Colin's announcement off-handedly: if Jo already suspects that Ruth and I are more than friends, I had better appear as nonchalant as possible. Turning back to my work, I had pressed the Play button, and the surprisingly clear sound of Ross's voice had issued into my headphones. Apparently, he and his wife had a lot of catching up to do after thirty years apart… old friends gone, new family members arrived, and amid all the minutiae that makes up the fabric of life, Ross was once more picking up the threads of his own. At one point, full of vodka and nostalgia, he had switched into Russian, and then I knew why Harry had given me this particular task: alone of all my colleagues in Section D, I am fluent in this language, having learnt it many years ago for a trip to that vast and complex country with my college choir, and kept it up ever since by regularly reading classic Russian literature. We had gone to hear, rather than to be heard: and it had been a humbling experience for us, as privileged students from Cambridge, to sit in those decaying yet splendid old churches, and listen to the finest choirs singing the ancient sacred music of the Orthodox faith. Even though Communism at its height had denied them religious freedom, it could no more stop the Russian people from singing than prevent the fall of the Berlin Wall; and their music, by turns as joyous, melancholy, and hauntingly beautiful as the land itself, had resonated deep within my soul.

I had paused the recording, rewound it, and made copious notes; the morning had flown by, even as at the back of my mind, I was reliving that moment in the tea room, over and over again: Ruth's cool little voice, her face expressionless, her eyes opaque and grey - always a bad sign - as she had looked at Jo and I. Oddly, I don't regret the actual moment half as much as I suppose I ought: hugging Jo was nothing like holding Ruth. I felt mildly avuncular towards her, if anything, and that was as far as it went. If she thinks that either Jo or I were capable of behaving like that, then that speaks far more to her character, than to ours, I tell myself over and over again, but the sick feeling in my stomach refuses to go away, and the unpleasantly familiar, tight sensation in my chest does not ease in spite of all my logical assertions. Nervously, I had turned the ring on my finger around and around, noting that the place where it sits was red and slightly itchy. Probably got a bit of soap under the band, I had thought, I must remember to take it off when I wash my hands…

My next task from Harry was to hack GCHQ – always a pleasure – and review access records for one Sally Curtis. We had received a tip-off that she was a mole for Korsakov, selling detailed analyses of the health sector in return for a partying lifestyle that hardly seemed befitting to a woman of her age and career; there was even a gigolo included, although it was thought that she didn't know that her too-handsome, too-attentive boyfriend was in fact a professional. I had taken myself through to the tech suite for this job, needing a bigger array and more powerful machines to run the highly complex coding needed to break through the GCHQ firewalls. It is at times like this that I feel myself become something other than my usual awkward, insecure self: I become calm, a creature of pure reason, binary logic flowing to my fingers as they move unerringly across the keyboard; my brain a biological interface with some of the world's most complex computers, yet retaining the uniquely human intuition and insight that gives me the edge as I decrypt layer after layer of security, working my way ever deeper, until I'm into the mainframe. I was well aware that my time inside GCHQ's nerve centre, the very heart of British intelligence itself, was limited; and the faster I'm in and out, the better my chances of going undetected. I searched rapidly through directory drives, looking for Sally's account profile, records and email traffic. I had copied the last three months' worth of outgoing messages and reports, while pulling the swipe access records to the building for the same time to corroborate times and dates. It had been a quick, dirty operation – a massive data dump and then exit stage left, no time for refinement; my blood was pounding in my ears as I closed out of their systems, erasing all trace of the worm I had used to infiltrate some of the most elaborate security in the country. Once safely back behind my own lines, so to speak, I had started to sort through the massive amount of information, throwing it across several linked screens as I began to make sense of it all.

On the screen to my left were Sally's emails; on the bottom middle screen, her financial work, and on the right, the building access records. On the topmost middle monitor, I was compiling connections and links between it all, using a rather neat little sorting algorithm of my own. Terabytes of raw data tumbled down the screens, looking rather like the graphics of an inexplicably plotted trilogy of films Colin had insisted on going to see as a marathon, a few years ago: it had been something bizarre called The Matrix, and my head had been throbbing by the time the final credits rolled… the effects, though, had been clever. I was happily sifting through everything, when something began to tingle at the furthest edges of my cognitive processes. Something completely unrelated to the task at hand, but important, nonetheless…something to do with the security swipe access records. Somehow, something was missing…

I had focused my attention on the right hand screen, scrolling through the daily logs of all movement in and out of Cheltenham, while racking my brain trying to identify the discrepancy. And then had come to me, flooding my synapses with a cascade of conflicting information: on the days over the last couple of months when Ruth has supposedly been attending a course at GCHQ, there are no records of her pass being used there at all. I had stared at the list of names and times onscreen: of course, she might be using a visitor pass, but that didn't make sense; her pass for Thames House gave her access to Cheltenham too, and she has clearance for both organisations, after all. What the hell was she up to, and why was she being so secretive? If she hasn't been attending the course as she claims, then what in heaven's name has she been doing? Before I had been able to ruminate any further, though, Zaf had popped his head around the corner. "We're getting ready to head out. See you in the van in five minutes?" I had nodded as I had saved the security swipe information from GCHQ into a specially partitioned portable hard-drive, and tucked the tiny device into the breast pocket of my suit jacket.

Jo had beamed at me from her perch atop a crate of fibre-optic cabling as I swung up into the cargo bay of the van next to her, and I remembered her first day on observation duty. "Sitting down this time, I see," I had observed wryly, and she had laughed back at me. "Yeah, I learned my lesson after I nearly landed on top of you!" Zaf had looked from her to me in confusion, frowning slightly as he handed me his laptop, displaying the blueprints of the penthouse at the Excelsior hotel, one of several London properties owned by our target. Once on the road, Zaf had swivelled round on his stool. "What do you make of that?" he had asked, pointing to the diagrams which indicate an unusually robust, three-phase power supply and a dedicated back-up generator on the top floor, something I had noticed when planning our surveillance. Colin and I had bugged the suite thoroughly a day earlier, and there had been something almost clinical about the space; starkly modern and white, it had somehow recalled the ambience of a server room.

I had shrugged, my mind still preoccupied with the mystery that is Ruth; such a power supply isn't unusual any more, not in this day and age of technology, and it is well known that Korsakov loves his gadgets. "He probably just wants to make sure he has an uninterrupted supply. And coming from the Russia in which he grew up, I suppose a back-up system is a luxury he wants, and certainly can afford, so why not?" Zaf had looked back at the screen, brow furrowing. "Sorry, but I'm not convinced. I guess we'll find out when we find out, though." Hearing this, one of Adam's favourite aphorisms, Jo had glanced round, and a shadow had crossed her face. "Buck up," I had whispered to her, feeling around in my pockets until I located my little tartan tin of butterscotch travel sweets. I had offered her one, then Zaf – I find they help when swaying around corners in the cargo bay of the van, as we were presently doing. Jo had taken one, Zaf had shaken his head, and in a few more minutes, we were on site, where we have now been for the last three hours, during which time Korsakov has come and gone from his eyrie twice, and returned with associates for meetings about which we know precisely nothing. Nothing. Everything had been going so well, and then Korsakov had picked up what looked like a universal remote control, and within seconds the live feeds on our monitors and headsets had turned into static and white noise, to our disbelief and dismay.

"Shit!" Zaf had exclaimed as the signals went down, "What's happening in there?" I had swiftly checked all our connections, just in case one of us had somehow knocked a lead loose: all was as it should be. Zaf had gone outside to check that there wasn't some other kind of interference at work, but short of the van suddenly having been encased in lead, I knew that the only reason for it must be the most sophisticated anti-surveillance technology I have ever seen, sickening though it is to contemplate; a kind of Faraday cage that appears to run throughout the entire suite. I have been working the problem ever since, as I have been trained to do, but the penthouse remains impenetrable to my best efforts, while Zaf and Jo watch silently, exchanging loaded glances with each other that don't escape my notice, even as I desperately try solution after solution, to no avail. Zaf's look says, Now what the hell do we do? Harry's going to go off! And Jo's replies, I don't know, but just give him time…my ribs feel too tight, and I have to concentrate on breathing normally in the uncomfortably tense atmosphere of the van. We don't have time, as I am all too keenly aware; and when a loud knocking sound erupts from the rear doors, my heart feels as if it is about to burst out of my chest with fright – Oh Lord, we're all about to be hauled away! Just as I think that I might actually pass out from stress, I spot a familiar face appears on the split-view monitor that shows all the external aspects of the van: Adam.

Zaf groans, "Oh, no!" but he knows we can't just leave him there, holding a carrier bag and grinning slightly manically at the camera above the door. Jo gets up to let him in, and the tension in the van goes up another couple of notches as Adam enters, bringing his own extremely peculiar emotional climate with him, as oppressive as a storm front gathering on the horizon. I lick my lips nervously: Adam should absolutely not be anywhere near here, in fact he should be at Tring, in my opinion. Like the born leader he is, though, he wants to know how things are going, and he's brought doughnuts to soften us up; he's cunning like that. Fortunately I don't like them, or care to have their sugary residue all over the place, so I decline as I answer him. "Korsakov's technology is a nightmare, he's turned the whole top floor into a high-tech paradise. Basically, it's a very advanced version of a Faraday cage, stops any hostile signal getting in or out."

Adam eats another doughnut, and asks, "But you've found a way of getting through it?" Ah, yes, here it is, the question I've been dreading. Cautiously, I reply, "Theoretically. Practically, I've no idea." Not quite true, but here's hoping it does the trick… Adam eyes me curiously, and it occurs to me that he's never heard me say that before. I'm the one they all come to for ideas, solutions, answers… As I ponder what, if anything, my current theory consists of, we see Sally's supposed boyfriend arrive at the steps of the hotel, obviously on his way to see my new nemesis. This will be interesting, I think grimly, bracing for the worst; and here it comes, as Korsakov settles onto the oversized white sectional couch. "He's switching the cage on… if I can just neutralise the signal I might be able to adjust our range to compensate…or perhaps if I try phasing the feed on alternate cycles…"but no-one is listening to me: I have always hated any sort of confrontation, and the low-voiced arguing behind me is making it hard to focus on my job. I'm feeling more and more nervous, when Zaf decides to exert his authority, and tells Adam to leave; Jo, reluctantly at first, but with growing conviction, backs him up, until he bangs angrily out of the van, Jo hard on his heels.

I keep out of it: field officers have their own interpretation of Five's rules and regulations, but I begin to feel physically sick, and not just because of my failure to crack the cage. Somewhere on the Grid, I know that Harry is watching... Is Ruth there with him too, and are they laughing as I try futilely to break through the cage? Is Harry even now drawing up my formal warning, or is Ruth managing him in that subtle way she has of turning him to her own thinking? Or are they...no, I mustn't go there, I mustn't think of that, or I will go stark staring mad with jealousy and grief... I am overcome with the urgent need to escape from the van, and lock myself into the nearest lavatory until I have retched and heaved out all my fear and insecurity. That's just too bad for me, though, because the next thing I know, Sally appears, headed for the hotel, and right on cue, her paid-up paramour comes trotting out towards her. She embraces him extravagantly, right there on the steps, and I glance at my watch, surprised to see that it's nearly five o'clock already: she must have left work early. Well, it is Friday, and silly little Sally likes to live it up with her man, such as he is, at a nightclub called Rumours, a trendy, faux-grungy establishment somewhere off the King's Road, after having dinner in one of the many restaurants that line this fashionable London street. Earlier today, Colin had slipped into the nightclub, under the guise of an electrical inspector conducting a spot check, and wired it for sight and sound. I hadn't even bothered suggesting I go: there's no way, even posing as an electrical inspector, that I would gain admission to such a place without arousing suspicion. It's my face, I think, that gives me away… Colin, on the other hand, is quite good at assuming a slightly seedy air along with a battered leather jacket, thickening up his North London accent towards something slightly more Cockney, and becoming what he fondly refers to as "Col the geezer." At heart, I know he's much more like me – steady, reliable, small-c conservative, and far too different to ever blend easily into a society comprised primarily of conspicuous consumption and people whose minds are both narrow, and shallow. It's why we get along so well together, but we're not entirely similar, and the differences are what make our friendship so rewarding, in my view.

Zaf mutters something in Urdu under his breath, watching the feed as Jo speaks with Adam in the street, until he gestures towards the van with his head, and turns away; evidently he has just told her to get back inside, for here she comes, her face awash with barely controlled emotion. Zaf pulls the doors shut behind her, and raps sharply on the wall between the cargo bay and the driver's cabin. " Let's go!" he tells Tim, our driver, who up until now has been happily reading the latest Tom Clancy thriller, while keeping an eye on the street; and with a sharp lurch forward, we're off in hot pursuit of Sally and friend, now in a black cab and headed towards Sloane Square. Resignedly, I pop another butterscotch into my mouth, and sit there miserably, trying to control my nausea as the van switches lanes unexpectedly, accelerates and decelerates rapidly, swings around corners and bumps over a quaintly still-cobbled section of road somewhere around the back of Chelsea, before coming to an abrupt stop. Jo and Zaf don't seem to mind, but I was the sort of child who grew queasy if I took too many turns on the roundabout in the playground, and things in that department have improved only marginally with the passage of time. Taking long, slow breaths, in through the nose, out through the mouth, while willing my stomach to settle, I turn back to the console, and get our bearings.

We appear to be in a service lane of some sort that runs parallel with the King's Road; two more seconds, and I know where we are to within a metre, as the GPS coordinates appear on my monitor. One day, GPS will stream information in real time; but presently, there is still a tiny delay between satellite and screen data. The van has pulled up in a loading zone, just behind Peter Jones, a rather nice department store: for once, it will not look out of place, but I can't understand why we are here, until I spot Sally leading the way down a steep, narrow set of stairs to a shiny, red-lacquered basement doorway opposite. Jo sees her too, and whistles. "She's not shy about spending her ill-gotten gains, then, is she?" Zaf chuckles, "Don't tell me you wouldn't go there if you had the dosh," and she looks indignant. "Please. I've got better things to do with my money than fork out for a few slices of overpriced raw fish." I look round at them in puzzlement, and Jo explains, "They're going to Fugu," as if that explains everything. They're going to eat the liver of a highly toxic species of blowfish? Jo sees my consternation, and hastily adds, "No, it's the hottest Japanese restaurant in London. I've heard that the sashimi costs a tenner per slice, and they serve it on little gold plates…" I blink, as much in relief that our target is not potentially about to poison herself, as at the outrageous price Jo has just mentioned, for a tiny bit of fish. Raw fish, at that; I feel ill again instantly at the very thought, and have to dab at my suddenly sweaty brow with my handkerchief. Japan has never been high on my travel wish list... give me Italy, or the south of France, any day.

"Is there another way out of that basement?" Zaf wants to know, and Jo says, "Want me to take a look?" Fingers moving quickly across the keyboard, I pull up the GPS map of the area and then, on another screen, the development application for the restaurant, which opened only recently. "Yes, it looks like there is, on the other side of the building. A staff entrance." Zaf nods. "Jo, you go for a recce, and take Tim with you, he could do with getting out of the van for a bit. He's to cover that entrance in case they take it into their heads to nip out the back way. Give him a set of comms and take that bloody book away from him first, will you?" Jo grins cheekily, picks up her rucksack, pops Tim's field kit into it, and hops out. We hear the driver's door slam shut, and watch as the pair of them set off, Tim moving stiffly after sitting for so long, Jo with her usual fluid stride. Ten minutes pass, then twenty; dusk has fallen, and I am beginning to worry, when we spot her coming around the corner in the opposite direction to where we had last seen her. She comes through the doors, muffled to the eyeballs in a very long, gaily striped scarf that reminds me irresistibly of Tom Baker's fourth Doctor.

"Cor, it's cold enough out there to freeze the…"I stop her there. "Jo. Good to see you back," I tell her, getting to my feet and pulling out the stool next to mine for her. She sits down, unwinding her scarf and taking her coat off. "It's lovely and warm in here, though. So, have I missed anything?" Zaf shakes his head. "It's a bit early yet for them to be leaving… what's that? Is that curry I can smell?" Jo laughs, unpacking the rucksack she has slung off one shoulder. "Mm-hm. There's a brilliant curry house just down the road, and I'm starving. Beef Vindaloo, extra hot, for you, Tandoori chicken for me, and a lamb Balti for Malcolm, extra mild, plus rice and naan all round. I might not be going out tonight, but why I should miss out on my Friday night fix? It's practically a London ritual, right?" The heady aroma of exotic spices and slow cooked meat fills the small, enclosed space, and after scooting our stools back a safe distance from the console that runs the entire length of one wall, we peel the lids from our meals, and wield plastic forks and spoons with as much gusto as if we were eating from silver and fine bone china. My stomach rumbles impatiently, and it occurs to me that I haven't eaten since I had that piece of toast this morning: no wonder I have been feeling so unwell. This morning…oh, bother! Mother will be cooking a big dinner tonight, and I have forgotten to let her know I'm doing double duty today. She does like to be told…

Hastily, I set my foil container down, and step out to call her. The house phone rings until the answerphone cuts in. Wincing at the sound of my own voice being played back to me, I leave her a message, before trying her mobile: it goes straight through to voicemail, so I leave another message, while puzzling over where she could be at 6:45pm on a Friday night, other than at home and making a roast dinner as she had said she would. Perhaps she's gone over to Evensong at the parish church, St John-at-Hampstead: she does that, sometimes, reverting to one of the habits of being a vicar's wife. Or maybe she has just popped out to the shops for a forgotten ingredient. At any rate, there's no more I can do right now, so after a quick side-trip into the gents' at Peter Jones - oh, blessed, blessed relief! - I return to the van, feeling strangely rattled by my failure to contact my mother. "You're just in time, Zaf was about to swoop on the rest of your Balti," Jo announces. He rolls his eyes at her and she responds by flicking a bit of naan at him. "No food fights near the equipment, if you please!" I caution, and Jo shakes her finger at Zaf. "Put that down!" she mock-scolds him, eyeing the ball of rice he is positioning on his fork, ready to return fire. And there it is, something intangible, but as real as rock, all the same: She likes him, just as surely as he likes her. Has Section D got another pair of star-crossed lovers on its hands? I wonder, methodically finishing my meal, using my naan to soak up the last of the delicious sauce, and then tidily packing the now-empty containers away into a garbage bag and tying it tightly closed, for there's nothing worse than the reek of stale food in the van. Zaf decides to wait in the driver's seat, in case we have to leave quickly to tail Sally to her next destination, a mile or so up the road; and Jo and I are left alone, watching as another Friday night in London begins for those who have finished work for another week, and are ready to let their hair down in a rush of eating, drinking, partying, and whatever else takes their fancy, here in this city of endless possibilities.

"Malcolm?" she asks hesitantly, and without taking my eyes from the monitors, I say, "Mmm-hmm?" Jo takes a deep breath, and plunges ahead. "This morning, you don't think that Ruth thought…I mean, that you and I…we…were doing anything, do you? I didn't get a chance to explain it, I haven't seen her all day. Anyway, you're well old enough to be my dad, so it's ridiculous if she thinks that…well, you know." Her voice is full of concern; touched, I turn towards her for a moment. "Ruth and I are just friends," I lie, hating myself for having to say it, but what choice do I have? "I'm sure she will understand that you were upset about Fiona. We all are, even if we don't always show it. Losing a colleague, a friend, like that, one never gets used to it, and you and Fiona were close." Jo listens and then nods, her eyes back on the screens. "I wanted to be just like her, you know. Fiona. So cool, like a spy out of a movie. Now, I don't even know if I want to stay in the Service… hey, can I ask you something else?" She is so very young, and when she speaks to me like this, I am reminded of the fact that I am indeed old enough to be her father… and very proud I would have been, too, to have had such a daughter. Smiling at her, I say, "Of course. You can always talk to me." I might not always be able to answer truthfully, but I will always be here to listen, I promise her silently. "It's about Zaf." Oh, yes? I think warily. "He seems to think that I would find things easier, you know, getting used to life in the Service, if I were to move into his spare room. Just as flatmates, of course. He's mentioned it a few times now, but I'm not sure. Is it usual, for officers to work and live together?"

I hesitate, choosing my words carefully before replying. "Well, there is certainly something to be said for having someone you can talk to at the end of the day, about your day, especially in our line of work. There have been quite a few officers here, over the years, you know, who had similar sorts of arrangements, and it seemed to work quite well for them. Zoe and Danny…they were the last that I know of," and here I falter, while a sharp pang of regret and loss passes through me at the memory of my friends, gone forever. Jo says thoughtfully, "Yes, but why do I sense that there's a But coming?" Goodness, she's sharp, I think admiringly, and continue, "The thing is, it doesn't work if both parties aren't honest about their motivations. If one person has…hopes…that they keep hidden, eventually things will take an odd turn. I'm hardly what you'd call an expert on relationships, but I do think it's very difficult for men and women to just be friends, under those circumstances; it becomes awkward for both, and excruciatingly painful for one. So for what it's worth, I'd suggest that you think very carefully before you make any permanent changes to your living arrangements, but rule nothing out, either. There have been plenty of long-term relationships, and even marriages, in the Service, that grew out of similar circumstances, you know." She nods, cheeks colouring delicately; and just at that moment, Sally and her companion reappear, and the real work of the evening begins as Zaf starts the van, and we follow them out of the laneway and down the King's Road to Rumours.

None of us notice Adam arrive at the club, an hour or so later: he's a past-master at counter-surveillance, and we weren't expecting to see him in the dark interior, and besides, we are all busily focused on the subject, getting very messy indeed, as Zaf puts it, with her fully paid-up lover, and then staggering out onto the dance floor. Zaf, sees him first, as Adam starts to move towards her. "No, oh, NO!" he groans, staring at the monitor with incredulity. Jo and I spot Adam at the same moment, and my heart actually skips a beat as I see him reach Sally. Puzzled, Jo says, "What is he doing there?" Covering my face with both hands in horror, I mumble back, "Ask me another." If this is Adam about to go rogue, I don't want to watch. Not after the ignominious ending that Tom Quinn had faced as he destroyed a career which promised to scale the heights. Poor, tormented Tom… I hope he found peace, in the end…him, and that poor American girl, Christine Dale. Now, there's a tale I won't be telling Jo…

Adam has got hold of Sally now, dragging her away from the main floor and into a corridor. She screams, fights, looks in vain for her lover, but he has already melted away into the crowd; and evil-doer that he is, he is not our target. Zaf growls, "I'd better get in there, stop him doing anything more stupid!" As he leaves the van, I see a strange expression settle on Sally's face; she's still frightened, but she's confused now too, and seems to be asking Adam the same thing, over and over, an oddly vacant look in her eyes. A look I have only seen in very advanced cases of dementia, or Alzheimer's… Adam's face shows his bewilderment at the change, and then realisation dawns on us both. "She's been hit with something!" I say under my breath, at the same moment that Adam says something very similar on-screen. Jo's big blue eyes gaze at me in horror, and back at the screen. "What?" Zaf is onscreen now, calling for an ambulance, according to the emergency services scanner in the van. "Drugs," I say shortly, "Not fun ones, either," as Sally collapses, her face as blank as a goldfish's, and now with the memory of one, too, by the look of things. A silly, treasonous mole she might have been, but undeserving of such a cruel fate, and I wonder who will visit her mother on Tuesday nights now… Ruth had mentioned that this was Sally's habit, part of her 'good girl, bad girl' routine, in her briefing, and that tiny snippet of irrelevant information had stuck in my mind. Perhaps because of the way Ruth had phrased it: good girl, bad girl.

And which, my love, are you? I ask her silently, as the van starts up and heads for home, or the nearest equivalent to home for most of us, given the amount of time we spend in the place. Jo had snagged the keys from Zaf, as he left Rumours with Adam and the ambulance officers who are wheeling Sally away, and when I had shaken my head at the offer to drive us, she had hopped into the driver's seat. I had slumped, eyes closed, in the passenger seat, as I tried to forget what was already searing itself into my memory for the rest of my life: the concrete knowledge that in this day and age, some things are still irreversible, some things cannot be fixed, and that not even all the King's horses and all the King's men can put a shattered mind back together again. At times like this, I fear that I have lived too long, and seen too much… So much pain, so much waste and senseless tragedy and destruction. Too much love lost, too much potential wasted… that's why I'm not willing to give up on Ruth. As long as we're communicating, in any way, shape or form, I believe that there's still hope for us. Hope, the one good thing that came from all the evil that Pandora loosed into the world.

I am totally done in after back-to-back observation shifts and the emotional stress of the day, and as Jo switches on the radio, my exhausted brain only vaguely recognises the song she is quietly singing along to, a song that I believe was popular a few years ago. A strange thing happens then: I seem to hear the lyrics as if the first time, and Jo's small, clear voice cuts straight through the fog in my head in which Ruth seems to dwell, of late. Struggling upright, I apologise as I quickly change the channel to a classical station, unable to bear hearing my own fears so accurately articulated; but the words revolve in my head long after the pop ballad has been replaced with the reassuringly majestic strains of Elgar's Nimrod, from the Enigma Variations…

It seems I've grown attached

Though we're not the perfect match

Should I stay, should I go?

Could I ever really stand to let you go?

Can you now find the words to say

That maybe I'm getting in your way…

Oh, Ruth.

A/N: The lyrics are from the UK singer Gabrielle's 2000 hit single, Should I Stay.