Mother is upstairs when I arrive home; standing in the kitchen as I make myself a nightcap, I can faintly hear the sing-song intonation of her 'telephone' voice. There is no evidence of cooking; the kitchen is as clean as a whistle, the dustbin empty. Frowning, I open the refrigerator, and blink in surprise: the shelves are stacked with Marks and Spencer ready meals. Mother hates ready meals, and has often railed against them when I have suggested she could buy some occasionally, instead of cooking every night. I don't understand anything any more, I think dispiritedly, carrying my mug of warm Horlicks spiked with Drambuie up to bed. Tired, but not yet ready for sleep, I look about for something to occupy myself with, and recall Colin's gift: I haven't watched any of it yet. The last episode I had seen had been the Christmas special, of course, which introduced the new Doctor, a gangly young Scottish actor with an impressive shock of brown hair. He had practically bounced through the screen with his rapid-fire speech and manic energy, and yet his performance had also been tempered by a certain sense of sadness and gravitas that bodes well for this, the tenth incarnation of the Time Lord.

When I was only a small boy, I had watched this very same programme, my eyes wide and my heart racing; both highly imaginative and very timid by nature, I would stare at the tiny, curved screen, willing the Daleks and Cybermen to stay safely in their own worlds, with the Doctor between me and harm. My mother didn't approve of me watching it, so I sat there with my father instead, pressed into his side and clutching my beloved teddy bear, Edward, unable to look away from the little black and white television set until the eerie theme tune had played over the closing credits. It was my father who would take me upstairs on those nights, my father who joined me in checking the wardrobe and under the bed for stray monsters, my father who would tuck me and Edward in and then say a prayer, my father's hand brushing my hair back from my forehead as he kissed me goodnight: is it any wonder then, that more than forty years later, I still love this most British of television shows?

I am less sure about the Doctor's current companion, even though Colin assures me that she's 'brilliant' and 'exactly what the show needed'. Well, that remains to be seen, but there's no doubt that she and the Doctor play well off each other, and that their relationship is …different… to any I can previously recall. Sitting up in bed, wearing blue striped pyjamas and with Horlicks in hand, I press a button on the edge of my bedside table, and the walnut panelling on the wall opposite my bedstead silently slides back to reveal a large, sleek black plasma screen. I reach over for my laptop, sitting on the pillow where Ruth's head would normally repose, and plug in the little blue Tardis USB, and a few seconds later, thanks to the magic of WiFi, I am swept up into a world of fantasy and excitement, full of strange creatures and weird aliens; a world where the Doctor can bring healing to an enslaved race of clone humans, or be possessed by a vampy, disembodied woman who refuses to accept the sad reality of ageing. It is every bit as mad and wonderful and enjoyable as ever, and by the time I have finished watching the first episode, my world is looking slightly less dire, even as I slide down into my big, empty bed. The Doctor is always about hope: hope against all odds, hope against hope. Hope, faith… and love. I don't know what's going on in my life, I have no idea where Mother was today, I don't know what kind of long game Ruth is playing or why, I'm up against the worst technological challenge of my life, with stakes so high if I think about them for even a moment, I'll be paralysed with fear, and I'm fairly sure that Harry still has it in for me; and yet, these three remain, I muse sleepily, darkening the privacy glass and rolling over to my side of the bed; a minute or two later, I'm out like a light, thanks to sheer exhaustion and a double shot of Drambuie.

The next morning, I am up and out of the house well before Mother is awake: I need to get back to the Grid and start working on a solution for Korsakov's ferociously effective security. I need to be at my makeshift workspace in the still calmness of the server room, away from everyone who might disturb me: I need to think. It isn't even six-thirty a.m. as I walk through the pods; I am the first one in, and after making myself a strong cup of tea, I leave a post-it on Colin's monitor to indicate where I am, and head through to the sterile, still silence of the server room, my secular cathedral, and, at this hour, my very own fortress of solitude. Sitting down at my little bench at the far end, tucked away between the stacks, I switch on the bank of monitors I usually reserve for running whole-system diagnostics, tapping directly into the raw power of the mainframe to run a realistic simulation of the Faraday cage. Based on what I believe the most likely scenarios are, I hypothesise half a dozen solutions: none of them are able to bring it down. The morning wears on, and so does my patience. I begin to feel that this is a problem beyond my abilities to solve: for once, I might actually have to admit defeat. Just as this thought flits through my mind, help arrives, in the form of Colin.

"Morning, mate. What are you doing, hidden away back here?" he wants to know, and so I tell him everything. He listens, and when I finish my tale of woe, lets out a long, low whistle. "Well, that goes some way to explaining why Harry's like a bear with a sore head this morning, then. Do you want me to take a look at what you've been doing, see if there's anything I can add?" I nod, grateful for his simple acceptance of the situation, and he pulls up another chair and begins to go over my work, muttering here, asking a question there. We pass some slightly more productive time in this fashion, before I catch sight of the time and start up in dismay: Zaf will be looking for me, ready to head out on surveillance once more. "I'm sorry, Colin, I have to go. I'm on obbo again." He looks up at me over his spectacles, his shrewd brown eyes gleaming with intelligence and good humour. "Well, at least we've got a couple of ideas to try. D'you want me to talk to C Department about it? There are one or two there who are good with electronics… and know how to keep schtum, too!" I smile back at him. "Thanks, I'd appreciate that." And then I am hurrying towards the door, and out onto the Grid – just in time, too, for Ruth, Jo, and Zaf are following Harry out of the briefing room. Ruth is very pale, her eyes downcast; the others look tight-lipped, and Harry does indeed look like a particularly bellicose bear, stumping along the corridor, jaw jutting and eyes almost black with repressed emotion. I glance at him, and then back at Ruth, and my heart feels as if it is in a vice. There's no mistaking that look; she's as guilty as sin, but of what? Oh, Ruth...

There's precious little time to dwell on what Ruth and/or Harry may or may not have done, though, for Zaf is already walking out of the pods, and I hasten to catch up. "Malcolm! Going out for lunch?" he asks, to my considerable confusion."Erm, aren't we due for observation duty at the Excelsior now?" Zaf shakes his head, about to step out of the Grid. "Haven't you seen your email today? That's been pushed back; there doesn't seem to be a lot of sense in it when we can't actually, you know, observe anything useful. Adam's been sent down to Tring, and I'm going with Harry to see a man about a dog... I'll be back later this afternoon, and we'll head out then. Gives you a bit more time to get that cage thing sorted, yeah?" and then he is gone. Yeah, I think glumly, and then something else Zaf said triggers my memory: I haven't checked my email since I first arrived at work. With no great enthusiasm, I do an about-face, and march back to my workstation. The first email that pops up on my main screen is from HR; the dreaded annual medical review has arrived, and I am to report to the CMO in half an hour's time: no excuses will be accepted. The Chief Medical Officer's word overrides that of everyone else in Thames House, up to and including the Director-General: I have been summoned, and so I must go.

At the outer limit of my patience with the world today, I let fly with a very rude word in Welsh, and Colin's face pops out from behind his monitors. "Steady on, there's ladies present!" nodding in Jo's direction. Colin knows nearly all the naughty words in both Welsh and Gaelic, having made a study of it while at university in an attempt to keep in good with the college rugby team, many who were from far-flung parts, and most of whom were residents on the same staircase as poor Colin, now standing beside me in concern, and asking "What's happened? Is it the Fara…" as he sees my despondent face, before he glances quickly at the open email on my screen, and nods in understanding. "Ah, right. I had mine a couple of days ago, actually. Looks like you'd better get into your PT kit, then. Good luck with it!" And with a friendly pat on my shoulder, he goes back to his work. Sighing in resignation, I lock my system, before heading out of the Grid and towards the staff lockers in the cloakroom to collect the hated kit. It is the only day of the year that I am ever to be seen wearing trainers and a tracksuit… I keep the wretched things in one of the lockers for just this purpose, and it is with deep distaste that I change out of my suit. To my surprise, everything feels bigger than I remember, and a look in the mirror confirms it: I have definitely lost weight. I had noticed my suits sitting a little looser lately, but hadn't paid it much mind. I step into the lift and go down three floors, to the CMO's chamber of torture.

"Hello, Malcolm! Do come in!" Dr Sally Chapman greets me a just a bit too heartily, for she knows that I detest the annual medical. I hesitate on the threshold, feeling ridiculous in my too-large tracksuit and bright white trainers, and then I step inside, and reluctantly surrender to her ministrations. First, she takes my blood pressure and resting pulse, followed by the electrocardiogram stress test, with me pounding away on the treadmill for dear life, stripped to the waist and wired up to a machine that beeps and flashes. I have taken the precaution of using my preventative inhaler, but even so my lungs feel ready to burst, and I am very relieved when the test is finally over. Because of my asthma, I have to do a peak flow test too, and tell her how often I use my medication. Still hot and sweaty from the ECG, I submit to having bloods taken and giving a urine sample; all things that one would rather not share with one's colleague, especially when that colleague is a very attractive lady doctor with red hair and a winning smile. As I step on the scale, her eye skims over me professionally. "Have you been on a diet?" she wants to know, looking at my pale torso, and then at the numbers on the readout. I shake my head, adding for good measure, "I don't always eat regularly when I'm on ops… life of a STO, you know. And I've been a lot more physically active since my last medical, so I suppose I might have lost some weight."

She looks up at that, and I see her eyes light up with scientific curiosity. "Really? What sort of physical activity?" And before I can answer, a tell-tale rush of heat floods my chest, and rises to my cheeks: damn, damn, damn my wretched Celtic colouring When I am finally able to meet her eye again, I am surprised to see that Dr Chapman is smiling at me kindly. "Well, that's wonderful! I'm sorry, but I have to ask: do you have a regular partner, or…" "Oh, r…regular, t…there's only one!" I stammer, blushing right to the roots of my hair. She nods and says, "And how long have you and…er…" "She", I supply, my face aflame. "Of course. And how long have you two been together?" Wondering why she is so interested, I answer, "Just over a year." Dr Chapman then enquires in a friendly tone, "And in that time have you been tested for STI's?" The true horror of the situation now begins to dawn on me as I say indignantly, "This is my first relationship, in a very, very long time; I'm completely clean!" The doctor steps closer, tape measure in hand, and says calmly, "Yes, but has she had other partners in the last two years?" before passing the tape around my waist, and then using a pair of calipers to perform a skinfold test; the instrument is cold, and despite the warm room, I shiver involuntarily. "Sorry," she breathes, taking the next measurement; and there is something about the way in which she is touching me, and in the way she was looking at me earlier, that I'm finding at once highly unsettling, and oddly exciting; it's almost like when Ruth and I are… I dismiss this thought immediately, with all the scorn that it deserves. I'll be as bad as Zaf, next, with his endless succession of S24 forms, even as he makes a play for Jo. Besides, what would a woman like her see in someone like me? She could have any man she wanted! And it would be totally unprofessional, unethical, un…Oh! I must be imagining thingsor perhaps I'm going potty… In a futile attempt to distract myself from the light touch of Dr Chapman's fingers on my right triceps as she takes the final measurement, I return to considering my reply to her earlier question, when it occurs to me: I don't know. Ruth has alluded to past lovers, but I don't know the names or dates. Come to that, I can't even be certain that she is being faithful to me… but then, I can't be certain about anything, when it comes to Ruth. I finally answer sheepishly, "I'm not sure."

"Right, you can put your top back on now. And do take a seat." Dr Chapman sits down at her desk as I comply gratefully, wondering why she has not yet dismissed me. Surely the medical must be over? "I'm just going to take another vial of blood, and I'll order an STI panel, as well as the usual tests. Better safe than sorry, you know!" She draws off the blood quickly, and smiles reassuringly as she asks, "How many units of alcohol a week do you drink? And how many cigarettes would you smoke?" Ah yes, the substance abuse questions... I answer as I always do, "A glass of red wine every night with dinner, for the antioxidants, and two on Saturday if I'm not on duty. I've never touched a cigarette in my life; they're filthy, stinking things." Dr Chapman makes notes, and then turns around to face me. To my surprise, she reaches over and takes hold of my left hand, examining it closely: I catch my breath at her touch. "Just slip that ring off, would you?" I twist it off over my knuckle, and she frowns. "Is it new?" I nod, "Yes, it was a birthday gift." She turns my hand this way and that; the skin where the ring sits is red and irritated. "Malcolm, I think you need to take it off for a while. You've got contact dermatitis." I look at the sore, cracked skin, as if seeing it for the first time. "Isn't there something that will clear it up?" Dr Chapman asks, "Is it that important that you keep wearing it?" Sliding the ring back on, I reply, "It is, to the person who gave it to me," after a small pause, in which I wonder if this is even a true statement. The doctor smiles, "Oh, I see. Well, I can give you a script for a topical cortisone cream; that should clear it up. You can't use it for too long, though, so if it doesn't clear up quickly, you'll have to remove the ring until your skin heals." She scribbles down the prescription and hands it to me; I make as if to get up, and she shakes her head. "Sorry, I haven't quite finished with you yet." Puzzled, I subside back into the chair and look at her expectantly.

"I have to be honest, Malcolm, I'm worried by what I'm seeing here. You've lost eight kilos – more than a stone, in old money – in the last year, when your BMI was perfectly healthy to begin with. You don't seem to have your asthma well under control, judging by the amount of medication you've been taking, and despite a marked increase in physical fitness, your peak flow results for lung capacity are lower than last year's. You're developing dermatitis, which you've never had before, and you've informed me that you're in a sexual relationship, which is a first in fifteen years of your medical history with the Service. I've done a cross-check with your HR record, and there is no S24 form on file, so I can only assume that you're involved with someone at Five. Intimate relationships within the Service can be very stressful, and stress is what I'm seeing here. So, have I missed anything?" She crosses one long, shapely leg over the other, and waits, while I try to think of an appropriately obtuse answer; but my mind is a blank. "Erm…" She taps her pen on the pile of paperwork requesting my blood tests. "Just to clarify: all this will tell me quite a bit, but I'm asking you how you are. Psychologically." I blink in surprise: all I can think of is being packed off to Tring… I mustn't speak, for if I tell her anything at all, I fear that I won't be able to close the floodgates of my anxiety over my relationship with Ruth, let alone my mother and whatever she's been up to lately. Cracking under this kind of pressure is what ends careers...

Dr Chapman leans forward and ducks her head to catch my eye as I stare fixedly at the corner of her desk. "Malcolm, I'm trying to help you. Anything you say to me will be treated in strictest confidence… please, talk to me." Her voice is warm, and I see both understanding and empathy in her cornflower blue eyes: it would be so easy to pour out my heart to her and tell her all about Ruth and my fears about Harry and how I love her but I don't know if there's a future for us, but I daren't, I just can't. Not today, with the weight of Korsakov's damned cage bearing down on me, and on top of that the future of the whole NH-bloody-S, and all our careers, to boot… these are the all too real monsters lurking under the bed now. Needing to get away from her steady, sensible gaze, I stand up, and she rises too. "Doctor, I appreciate your concern, but I'm fine, r…really I am. And I'm sorry, but I have to get back now… thank you for your time." Just as I'm about to escape, she says, "Malcolm?" and I look around, my hand already on the doorknob. "I'll let you know when the test results come back. Take care out there, won't you?" She gives me another of her blindingly bright smiles then, and again I find myself thinking what an attractive woman she is: in her early forties, or so I judge, tall and elegantly dressed, with what my mother would call an old-fashioned figure, and the most glorious mane of auburn hair. She's like a screen goddess from the Golden Age of Hollywood… I have no idea what such a beauty is doing here in the basement of Thames House listening to portly, middle-aged desk spooks lie about their consumption of alcohol (hardly any) and the amount of exercise they do each week (oh, lots!), but suddenly, I'm very glad that she is. "Thank you," I reply with sincerity; and then, I'm out in the corridor, and free.

Once I'm safely back in my suit, I head towards the staff canteen; Faraday cage or not, after the morning's exertions, I can no longer ignore my nagging hunger, and at least they do a passable Coronation chicken sandwich. Waiting patiently in line, I feel the tiniest tug on the sleeve of my suit jacket, and glance down to find Ruth at my side, looking straight ahead. "Just act normally," she says under her breath, and I fight the temptation to laugh out loud. What does she think I'm going to do, ravish her here in the lunch queue, or start a blazing row? Her eyes beseech me to cooperate; I see real fear in them, and I begin to wonder if perhaps I've been reading the situation between us all wrong. Women, after all, are hardly my area of expertise…and besides, all my gentlemanly instincts oblige me to at least make the invitation…'play up, play up, and play the game', and all that… "Ruth! I didn't expect to see you here…would you care to join me for lunch?" I say lightly. She smiles briefly, and nods. "Yes, but I don't think there's anything I fancy here." Well, that's too bad, because it's here or nowhere... "I'm a bit time-poor today; got a lot on, I'm afraid. A sandwich and a cup of tea is all I have time for, but you're welcome to sit with me, if you like."

We're at the head of the queue now, and I pick up a tray, plonk a triangle-pack of sandwiches on it, and slide it along the rails towards the beverage station. Ruth hesitates for a second, before taking a tray of her own, putting a soggy-looking slice of tightly cling-filmed apple pie on it, and following me. She asks for a cheese and tomato toastie, and then joins me where I am making tea. "May I make you a hot drink?" I ask politely, and she has the grace to blush as she says meekly, "Yes, hot chocolate, thanks." With our paper cups perilously full of indistinguishable brown liquid, we move our trays toward the cashier, where I pay for mine, and she pays for hers: that's the usual thing when colleagues have lunch at work, isn't it? Ruth chooses a table against a wall, midway down the room; it is still early for lunch, and no-one else is sitting nearby as we take an uncomfortable plastic chair each, and I use my flimsy paper napkin to dust the crumbs of previous occupants off the tiny metal table. The staff dining room at Five was once a sight to behold, but now see how the mighty have fallen, with successive budget cuts and endless talk of efficiency dividends over the years. I say as much to Ruth, and she looks at me with interest as she extracts her limp-looking toastie from the confines of its foil-lined bag. History, of any kind, is one of her abiding passions… How it that I can know her so well, and yet not know her at all?

"Really? What was it like?" she enquires, taking a bite. I take the cellophane lid off my own sandwiches, and wrinkle my nose slightly at the prospect of actually eating the curly-edged, under-filled, dry-looking things inside, which are patently not Coronation chicken – in my haste, I have managed to pick up a cheddar-and-chutney, instead. "Oh, you know. The usual sort of thing: heavy white china with the Service's insignia on it, proper glassware and cutlery, none of this disposable stuff. Tablecloths, and waiters to lay them, too. A menu that required actual cooks to prepare it, instead of this dismal heat-and-serve rubbish that's been foisted upon us of late. Oh dear, I'm starting to sound like a relic from another age, aren't I?" I joke weakly, and she shakes her head. "No, I'm fascinated, truly. If you're not going to eat that sandwich, why did you get it?" I look down at the tray before me, and back at her. "You really are the most impossible snob, you know. I bet if that had come from Harrods or Fortnum and Mason, you would have eaten it and gone back for more. D'you want to go halves in this?" she offers, disinterring the apple pie from its cling-film shroud. "I am not! And no, thank you," I reply indignantly, picking up half of my sandwich and biting into it, before washing it down with weak tea. Talk about the sweepings from the floor…where do they get this undrinkable muck?

Ruth chuckles, the low throaty sound that I love, and despite all my fears and nameless misgivings, my pulse begins to quicken as I look at her across the table; her reference to my being a snob has brought memories of that remarkable trip to Bournemouth flooding back. We had been so happy then… hadn't we? "Oh, I'm afraid that you are. Dyed in the wool, in fact." She is smiling, though, and on a mad impulse I ask, "Ruth, are we… all right?" She sits back in her chair at that, and gives me a long look, her eyes like searchlights in a most improbable shade of blue-tinted green. Finally she says, in a voice so quiet I have to lean forward to hear her properly, "Jo spoke to me this morning, and explained that she'd had a bit of a wobble about Fiona. I can understand her going to bits on you, because you're so very good at putting everything back together again, but Malcolm, you need to be careful. Harry… he's under enormous pressure with this op, and he's already marked your card for you once. Believe me, he was less than delighted yesterday when the surveillance went down, and if he thinks that your attention is anything less than one hundred and twenty per cent on the job, he's likely to take some fairly drastic action. You're the one he relies on to get things done, to solve the unsolvable; you can't afford to be side-tracked, not even to help others. You've got to put yourself first for once, at least until we're clear of Songbird; if we don't get this one right, we'll all go to gaol. Harry said so himself, and it scared the life out of me."

I regard her across the table: Is this what she has been doing recently, then? Putting herself first, for fear of the consequences should Songbird fail? Why is she so extremely worried about this particular op, and why did she look so guilty as she followed Harry out of the briefing room this morning? "Ruth, I know this isn't the time or the place, but just so that I can stop worrying about it every waking moment, I'd appreciate a simple yes or no answer: are you and I all right? And I don't mean from an operational standpoint." Her expression changes in an instant, the shutters going up as she sighs, "Don't, Malcolm; please don't do this now." My breath refuses to come:"Ruth, please," I finally manage to choke out. She fidgets with the detritus of her lunch, lying on the table between us, and at last she says very softly, "I don't know." I stare at her, dumbstruck and disbelieving the evidence of my own ears, until the force of my gaze makes her look at me; slowly she raises her eyes, and I feel my gorge threatening to rise too. In my stunned state, a random line of Shakespeare drifts through my memory: My mistress' eyes are nothing like the sun… After an interminable silence, Ruth gets to her feet, picks up her tray, pauses by my shoulder to whisper, "I'm so sorry," and then she is gone, leaving me to drown in the shockwaves of emotion that have begun to roll in over the top of logic, sense and reason. Never mind not being side-tracked: with those three little words, I've been blown sky-high. The song I heard last night on the radio echoes again in my ears, and I feel a very great need to hide myself away from the world. Preferably forever...

Instead, somewhat to my surprise, I find myself back at my makeshift desk in the server room, staring dully at the screens in front of me. Shock affects people differently, I know, and I suspect that mine will be of the delayed variety: like a soldier on the front lines, I have no option other than to keep pushing forward through this operation, putting one foot mechanically in front of the other until I'm out of no-man's land: my training and my conscience demand no less. In a couple of hours' time, I will be back on surveillance duty, and with that thought, and spurred on by the threat of the extreme unpleasantness that will undoubtedly descend upon me from a very great height should I fail to defeat Korsakov's painfully good technology, I force myself to focus on my work. Closing my eyes, I imagine my consciousness as a vast server farm, and then, just as I would remove a virus from any network, I deliberately partition off my feelings about Ruth behind the firewalls of my aching heart. Compartmentalisation, I believe the psychologists call it; and it is a very necessary survival skill to cultivate, in this line of work. We all do it to some extent, or none of us would have ever set foot back on the Grid after our first week; and when I can once more breathe normally, when my hands have stopped shaking and I no longer feel the hollowness in the pit of my stomach, I open my eyes again, and begin to work on the problem before me with the cool efficiency of a machine. A very human machine, that is, with a rag and bone shop for a heart…

The absolute last thing I want is to revisit the scene of my defeat without having a solution for the Faraday cage, but despite my best efforts, here I am, some time later, sitting in the van once more outside the Excelsior, and knowing that for once, I don't have the answer. It is a sickening thought. While we wait, Zaf paces up and down the length of the cargo bay, and Jo and I look at each other, uneasy at his palpable annoyance. "It could be worse, Malcolm," she says after a minute or two, "you could have been in the briefing this morning, getting accused of indiscipline… I've never seen Harry so cross!" Zaf looks at her warningly, but Jo ignores him. "It was awful, Harry thinks that one of us has been passing information about the operation to Adam… if he finds out who it is, he'll be livid." A thought occurs to me, and I ask, "Do we know what Sally was hit with? I presume a psychotropic of some sort?" Jo stares at the screen in front of her; in a very small voice she tells me, "Yes, they ran toxicology tests last night. It was something called anaoxide diethylamide. It wipes your memory… just destroys that whole part of your brain." I nod, "Yes, I know. It was one of the more refined paths that chemical warfare went down for a while. We made it, and now it seems that the Soviets did, too." Jo turns to me, shocked. "'Refined paths'? Bloody hell, Malcolm, you almost make it sound like it's a good thing!" I blush; sometimes I forget that not everyone looks at things as I do, through the twin filters of science and logic. "Of course that's not what I meant; I think it's a dreadful thing to do to anyone. It's only that, for the time, it was an innovative way to approach the problem, when compared to some of the other chemical weapons they were coming up with on both sides, most of which were just hideously lethal. Sarin gas, for instance…"

Jo shudders; in an attempt to explain my position, I continue, "Jo, I'm a scientist, first and foremost; I studied chemistry and physics, and so I tend to think differently about things like this. It doesn't mean that I approve of something on a moral level, just because I recognise it as a potential solution to a potential problem, any more than… than I think that Jonathan Swift was really advocating that the Irish eat their own children!" Jo blinks, thrown off-kilter by the unexpected change in conversational direction, and then she gives me the tiniest hint of a smile. "Oh, you mean like in A Modest Proposal! I'm sorry, Malcolm. It's just that you gave me a bit of a scare for a moment there. I've not seen that side of you before, and I'd forgotten that you're not just a techie." I give her a tiny half-smile, relieved that she understands, or at least is making the effort to, and then Zaf says impatiently, "All right, enough chat. Let's focus on the operation, and on not letting this smug bastard wreck the NHS. Malcolm, what about his blocking device?"

I reply succinctly, "Not turned on yet. It's common protocol, it gives people like me less time to crack it." I know Harry is listening in; he has somehow managed to convince Hugo Ross, of all people, to work with us in bringing down the rabid capitalist dog Korsakov, an idea that is either sheer brilliance, or utter madness; sometimes, in this job, it's hard to tell the difference. Zaf speaks to Harry over his comms, assuring him that we will patch the surveillance through to him, as we observe the formidable figure of Ross mount the steps of the Excelsior. Korsakov, meantime, is talking volubly and vacuously about nothing – trainers, apparently, as Zaf mutters to Jo – and then we are watching the first meeting between old ideologue and young oligarch. I am fascinated by the interaction between Ross and Korsakov, but Zaf is less than impressed, and I realise that for all his many excellent qualities, our Mr Younis has absolutely no sense of history. Impatiently, he wonders what Harry is looking for. I could tell him, but decide to keep my own counsel; I am watching Korsakov like a hawk for any sign that he is about to activate the cage. After my morning's work, the best I have been able to come up with are some phase modifications that may allow me to harmonise our signals with the specific electronic resonance of the Russian's fiendishly clever device; I am in no way confident that it will work, but it's all I've got.

Ross is getting worked up now, even though he's just been offered a job: he's verbally lashing into Korsakov with all the pent-up fury that can only come from spending the best thirty years of his life behind bars for his beliefs… and then it happens. The sound in our headsets starts to crackle, and the video feed begins to break up; my fingers move frantically across the console. "Malcolm," Zaf says tersely, and I reply, "I've adjusted the phasing, this time we'll… " I stop, holding my breath as the feed stabilises for a few seconds; have I actually done it? And then it all comes crashing down in a blur of static and white noise. In my other earpiece, Harry's voice, as clear as if he is sitting in the van with us, growls "Malcolm!" in a manner that tells me I'm for it, again, if I don't perform a miracle; but I'm already doing everything I can think of. "Oh no. No! Damn it!" I cry, beside myself as the signal fizzles out; in my earpiece, the silence is at once deafening, and menacing. Harry, it would seem, is Not Happy. I review the last few seconds of data, trying to glean any little snippet of information or insight, but it is no good: we are locked out of the penthouse as effectively as if we were no more than children, scrabbling to reach the doorknob.

In an act of almost suicidal defiance, I remove all my comms, turn off the van's external cameras, and stride outside: I need a moment to myself, or I may not be answerable for my actions. In supreme frustration, I actually go so far as to deal one of the rear wheels a solid kick, imagining it is the Faraday cage; a sharp pain shoots through my toes, and I hop around in the deserted street, swearing under my breath. It is undignified, it is unprofessional, and at this particular moment, I cannot find it in myself to care. Just as I am about to limp back on board, my personal mobile vibrates insistently; extracting it swiftly from my pocket, I hastily flip it open when I see the caller ID: Aunt Emily. She hardly ever calls me on my mobile… "Hello?"

Five minutes later, I haul myself up into the back of the vehicle and take my place, backing up the surveillance recordings we did manage to capture, packing up comms, and going about my work without a look or word to Jo or Zaf, who shortly take themselves around to the drivers' cabin, leaving me alone in the back. Jo lays a hand on my shoulder as she passes, giving it a gentle squeeze, but when she says, "Malcolm," sympathetically, I tell her, "Don't," in a flat voice, staring straight ahead; silently, I add, just leave me alone! And sure enough, she does. Hunched unhappily on the floor against the cargo bay wall as the van pulls away, I relive the conversation I have just had with my aunt; the upshot of it is that my mother has taken herself back to Bournemouth today, lobbing up on my aunt's doorstep to drop off her bags and claim the newly redecorated spare room for herself; she had then swished out the door in her mink coat, and into a waiting cab, and hasn't been seen since. Well, that explains the fortnight's worth of ready meals in the fridge, I had observed cynically, listening to Aunt Emily's concerned voice. "She just didn't seem like herself, love. Are you sure she's been taking all her medications? And where in heaven's name did she get that coat?" Sighing, I had replied, "I know, she's been most peculiar lately. I think she's met someone down there, but I can't get any sense out of her. If she's staying with you, though" - and here I had shuddered at the recollection of the hotel bill I have just paid for her last sojourn at the seaside – "she might just talk to you." Aunt Emily had promised to do her best, and then had rung off, leaving me staring at the handset, and wondering what else could possibly happen today. I should have remembered my father's injunctions against tempting fate…

As soon as we arrive back at Thames House, I head off by myself to the tech suite, despite the lateness of the hour. I don't have a clue about what to do next, and my head feels as if it is about to split, but doggedly, I sit down, fire up the array, and start once more from scratch. I'm struggling to maintain my objectivity now, as the emotional stresses of the day threaten to break through my thin veneer of calm; but I'm hard at work when Harry appears in the doorway. I sense, rather than hear, his soft-footed approach; and every muscle in my back and shoulders tenses against the inevitable bollocking that's coming my way. Stubbornly, I refuse to turn around and look at him: I've simply had enough, and I don't care who knows it. When he speaks, it is to taunt me, or so it seems to my hyper-sensitive ears. "So Korsakov has got the better of you and the whiz techies of C Department." It is a statement, rather than a question; and there is something so insufferable about the strange smugness in his voice that I snap, "At this point in time… this is the worst day of my life!" Although true, I immediately regret my outburst: I have displayed a weakness that I know will not go unnoticed, and sure enough, he barks back, "Well it's not over yet. Fix it!" before he walks away. Provoked by this unnecessary order, and furious at my own impotence in the face of Korsakov's technical superiority, I snarl soundlessly at Harry's retreating back, like a dog that has been unfairly chastised by its master, but knows it mustn't bite the hand that feeds it.

Desperate to find a way through, I work all night alone in the tech suite, which is where Colin finds me, red-eyed, unshaven and exhausted. "Morning, mate!" he greets me cheerfully, and I grunt in reply, rubbing my hands over my face blearily, too tired to even get up as he approaches; my nostrils twitch, though, as he sets a grease-spotted brown paper bag down, emanating the tantalising aroma of bacon. A tall, lidded cup joins it, sending forth the brain-jolting scent of strong coffee, and quite suddenly, I am ravenous, as I realise that the last thing I ate was that dreadful sandwich at lunch yesterday. I push the memory of Ruth away with a sort of weary determination, and fall to, as Colin drops into the seat next to me. When I am halfway through my breakfast, he places a sleek black USB stick onto the desktop with a flourish; his eyes gleam from behind the thick lenses of his spectacles, and after a moment, he says, "Well?" with a grin he can no longer suppress. "Well, what?" I reply grumpily, and then, ashamed of my curmudgeonly behaviour, I add, waving at him with my bacon sandwich, "Thanks, I think you just saved my life. How did you know I'd still be here?"

Colin looks at me reprovingly over the top of his specs. "Oh, please. Where else would you have been, after what went down last night?" he asks impatiently, before saying again, "Well?" his grin widening as his glance flicks from me to the USB, and back again. There's something in the way that Colin is sitting, a kind of suppressed nervous energy; my spirits begin to lift, just looking at his honest, intelligent face. "No, tell me you haven't…" I begin, and he nods rapidly. "Yes! Or at least, I think so. You're not the only one who's pulled an all-nighter, you know. It's a spike program… C Department ran the numbers, and I took it from there. We still need to test it with your simulation of the Faraday cage, but I think this will do the trick…" Frowning, I remember something that Colin had mentioned yesterday. "But didn't you say Arsenal was playing at home last night?" He flushes slightly. "Well, yeah, but this was more important. Anyway, my nephew got to go on my ticket, instead, so it's all good." I don't know what to say: my best friend has given up an all-too-rare chance to see his beloved Gunners in action, in order to help me out. Humbled doesn't even begin to cover how I feel. One of those moments that only occur in longstanding friendships such as ours, in which everything is said and understood without a single word ever being spoken, passes between us, and then I pick up the USB and plug it into the nearest machine. After a minute, I say "So, let's see if it works," in my normal voice, and together we start testing the spike program against the Faraday simulation.

It works: Colin's spike program works! It is at once mind-numbingly technical in its concept, and beautifully simple in its execution, as befits a work of genius. After analysing the results of a series of simulations, I make a few refinements, trying not to think about the hideous, but all-too-real possibility of encountering a back-up system. Testing complete, I drag myself into the dogbox at the back of the Grid for a few precious hours of shut-eye before I shave, shower, and change into a clean shirt, ready to join Zaf, Jo, and somewhat to my surprise, a newly reinstated Adam, back in the van on observation duty. When I emerge from my ablutions, feeling slightly more presentable, neither Harry nor Ruth are anywhere to be found on the Grid, and for once I'm glad of it: I don't feel up to seeing either of them at present. On the way down to the garage, Jo fills me in on what I have missed: Adam has checked himself out of Tring, declaring that he is ready to come back to work, and Harry, running out of time and in need of a definitive result, has decided to raise the stakes and play Hugo Ross against Korsakov in what seems to me to be a risky move with potentially disastrous implications for us, Ross, and the entire NHS if it all goes wrong: and everything hinges on whether I am able to defeat the Faraday cage. "No pressure, there, then!" she finishes, with a smile that doesn't quite wipe out the worry in her eyes.

I am the last one into the van, having stopped near the lift shaft for a discreet puff on my inhaler, in an attempt to disperse the tightness and shortness of breath caused by exhaustion, stress and anxiety: I try not to think of Dr Chapman's concerned face as I dose myself yet again. "Come on, slow-coach," Jo jokes, watching me walk tiredly across the garage floor, "We need you!" And somehow, hearing her say those words – the same words that I had spoken so encouragingly to her – makes me feel that little bit better. They do need me, I remind myself, and a steely resolve to beat Korsakov at his own game rises up from deep within. I will not stop until I crack that damned cage, I promise myself, sitting down on my accustomed stool in the cargo bay; Jo is in the back with me, Adam and Zaf are up front. "Are you OK?" she wants to know, and I smile at her. "Oh, I'm always alright," I tell her once again, but this time I mean it. I will not allow myself to be defeated by some Russian robber baron and his obscenely expensive technology: what one mind has devised, another can destroy, and destroy it I will, thanks to Colin and his tireless dedication. No sooner have we closed the rear doors, than the van shoots forward: Zaf must be driving. Resignedly, I retrieve my little tartan tin, and offer it to Jo, as we sway on our stools. "Butterscotch?"

In no time at all, it seems, we are parked back outside the Excelsior, and I am conducting the final technical checks before we make a last-ditch attempt to trap Korsakov. Talking more to myself than to my colleagues, I mutter, "We have visuals, we have audio - game plan on." Adam glances at us all, and true to his ability to joke about even the worst situations, he murmurs, "Right, we screw this up and part of England disappears." Jo looks at him, unamused, and on the monitors I watch Zaf meet Hugo Ross on the kerbside: And we are go for the final stage of Songbird, God help us all. The two men have no difficulty in accessing Korsakov's suite; and from the second they set foot inside, I am on tenterhooks, waiting for him to pick up that fake remote and activate the Faraday cage. Every muscle in my body is tense, and I feel slightly ill with anticipation. As it turns out, I might have just as well laid my head down on the console and gone back to sleep, for Korsakov proceeds to talk about himself for the next seven hours, which must surely be some kind of record. Adam calls him the 'exploding ego', and I silently concur, as the man bores on about the minute details of every aspect of his early life, in the belief that Ross is going to write his biography.

After the first two hours, it has grown so warm in the van that I actually take off my jacket; after the next two, I loosen my tie. Jo, sitting next to me, perfectly sums up what we're all feeling, three hours later. "That man has talked non-stop for seven hours! He should be deported for yapping." I couldn't agree more… Just when it seems that Korsakov is about to dismiss them for the day, things finally become interesting; cleverly drawn out by Ross, he starts to boast about how he is 'continuing his father's work', and we all sit up; is this it? But the man is a cunning little weasel, and as soon as he starts in this vein, he stops. "Is there nothing we can do?" asks Jo anxiously, and Adam says bluntly to me, "Have you got his mobile number?" I bite back a snarky retort (of course I do, don't I always have everyone's details on ops?) and answer simply, "Yes." Adam flicks a glance my way. "Dial it, now!" I do it with alacrity, and one of the most brilliant bits of improvisation it has ever been my pleasure to observe unfolds, as Adam tells Hugo to become a double agent, under the pretext of a call from the old man's estate agent.

I had been rather perturbed, upon being sent to bug Ross's house, to find that he lives just a stone's throw away from me, over in Hampstead village; he had inherited the house just before he was sent to gaol. Well, there goes the neighbourhood, I had told myself philosophically, while installing my devices; if an old Soviet spy can live in Hampstead, then what next? The IRA in Highgate, perhaps, or a houseful of Islamic radicals in Mayfair? Now, though, I am riveted by that old Soviet spy's performance, and I can see why Harry has always considered Ross to be a very dangerous man. He is bold, believable and utterly committed to the part he is now playing – if, indeed, it is a part. Seeing Korsakov reach for the remote, I rush to load the spike program, my heart beating against my ribs as I shoot a tiny prayer skywards. Dear God, please, please, please, let it work… I promise I'll be good forever, if You will only grant me this one thing. "Here comes the cage," I announce in agonies of anticipation. "Theory, become reality," I plead, as the spike appears to take effect: and then, horribly, the screens begin to snow, the sound begins to crackle: Oh NO! I plead with the Almighty, "Please, please," while frantically boosting the signal. "Is it working?" Jo asks quietly, and I mutter, "I always kept this quiet, but I had my doubts about a backup system…" Alarmed, Adam shouts, "WHAT?" at the mention of a backup system, and then, as I adopt an attitude of supplication, a beautiful thing happens. The visuals become sharp, the sound returns: yes, we're IN! Feeling positively giddy with relief, I declare, "I've done it! Success is with me!" Oh, thank You, and thank Colin, and C Department too, I add mentally; it won't do for me get too carried away.

Which is exactly what Ross appears to be doing: I watch, appalled, as Hugo burns Zaf's cover, and then sets upon the young man, delivering several brutal kicks as he lies curled on the ground. He'll have broken ribs, at least, if not internal organ damage, but none of that will matter if Korsakov shoots him, as he evidently intends to do. I can hardly bear to sit in the safety of the van, passively monitoring the action; and it proves more than Jo can take. "Adam, they'll kill him!" she protests, but he ignores her, for it's now or never, and Ross plays Korsakov masterfully, antagonising him with all the contempt that only an old-fashioned Communist could have for a robber baron, until Korsakov begins simultaneously to boast of his plans to destroy our 'pathetic little socialistic health service' – building carparks and casinos on land where hospitals currently stand are just two of his innovative ideas – and to threaten to inject Zaf with anaoxide diethylamide like Sally Curtis. At that, Adam judges it time to act, to my immense relief. "That's it! Send 'em in!" he orders as he bursts out of the back of the van like a jousting knight coming out of the lists, charging to the rescue. I give the command, "Delta Six to Mercury One, activate all units!" and with those eight words, unleash the might of the British state: SO19 swings into action, and in seconds it's all over. At first I think all is well, and then I hear Zaf say, "He's been hit with a needle!" No, oh no. Not Ross, he doesn't deserve this, not after serving his time and then serving his country so bravely, on this most dangerous of operations… Fortunately, I had ordered a vial of the antidote prototype to be sent from Porton Down, just to be on the safe side, and Adam swiftly deploys it; Ross looks bemused, as well he might, but the immediate destruction of his frontal lobes appears to have been averted.

Special Ops bundles Korsakov away, and a minute or two later the ambulance officers arrive to take Ross and Zaf, badly hunched over on one side, off for treatment; only Adam is left in the room as Jo and I, moving slowly after having sat still for so long, start to pull on our coats, preparatory to leaving the cargo bay. My shoulders are tight, my neck is stiff, and my heart… well, my heart is better not thought about. Just as we are about to leave, I pick up an inbound call to Adam's mobile; out of habit, I sit back down. I had nearly forgotten that Harry has been monitoring us from his office the entire time; he has called to congratulate Adam on the successful outcome of Songbird, his voice warm as he lauds his senior field officer, while Adam sinks to the floor inexplicably, his shoulders heaving, his voice breaking… I have never seen Adam in anything less than perfect control of himself on ops, and it shakes me to the core. This must have been how he was after Fiona…

"Malcolm, will you wipe that last bit of tape?' Jo asks softly, but there is steel in her eyes; I hesitate, aware that she is asking me to destroy operational evidence, but then I remember all the times that I have wiped inconvenient little bits of footage on my own behalf, or on Ruth's, in the last year, and decide that Adam is entitled to this moment of privacy, and press Delete, backing it up to the point just before Adam takes out his phone to answer Harry's call. My ring glints in the light of the monitor as I do so, and I realise that the flesh on either side of the band has become flaky, red, and very, very itchy; belatedly, I recall Dr Chapman's advice, and wincing, I work it off and drop it into the breast pocket of my suit. There doesn't seem much point in wearing it now... the heavy ring clinks against something hard, and in puzzlement, I feel around in the pocket until I find the tiny USB of GCHQ security swipe records; I had forgotten to take it out the other night, but now I recollect why I have it: Ruth. What has she been up to, all those times that she said she was going to Cheltenham for training? And why can't she tell me about it, or what she has been using the Tessina for? And… "Malcolm? Are you coming?" Jo's voice, as it breaks into my thoughts, is mildly impatient, and I realise that I have been in my own little world for the last couple of minutes. "Of course, sorry. I was miles away." Jo nods, watching me with those big blue eyes. "Yes, you were. Tired?" she replies, watching as I get up unsteadily and groan, arching my back to ease out the kinks in my spine; my whole body aches unpleasantly from too much sitting, but the physical pain is nothing to the emotional turmoil that is roiling just beneath the surface… I will not feel, I will not feel…what you don't acknowledge can't hurt you…

"Very," I admit, uncharacteristically. "C'mon, I know just the thing to sort you out," she says, and before I can think of an excuse not to join her, she is leading the way towards the King's Head, just across the road.

Well, it would be wrong to allow a young lady of my acquaintance to drink alone…

I step out of the van, gasping as the bitter air of the mid-February night catches in my throat. I know that I should really go straight home, or straight round to Ruth's to try and find out what she had meant…

Wouldn't it?

I follow Jo inside, and into the warmth.

A/N: Malcolm is thinking of Shakespeare's Sonnet 130, during lunch with Ruth. The line about 'play up, play up and play the game,' is from the poem Vitai Lampada, by Sir Henry Newbolt.

And just to clarify, 'going potty' in this instance is not what toddlers do; he could just as well have said that he was going barmy, bonkers, or round the bend. But this is Malcolm, and he tends to use an old-fashioned turn of phrase, so 'going potty' it is... by the way, he's not.