Even though intelligence work is the only career I've considered doing since my forced session with the patronising careers advisor at upper school, the thought of my first day at Section D didn't exactly fill me with delight. I would be the outsider once more, with the blood of one of their officers sort of on my hands, and probably easier to dislike than your average Henry double-barrelled smoking cigars at the thickly-curtained windows in Whitehall.

I had been told that an 8am arrival would be fine, but a night of little sleep and a desire to get the process over and done with ensured that I had devoured a black coffee, pulled on my heeled boots and marched into the Tube station little before seven. I had been to the Grid before, during the attempted coup-d'état orchestrated by my father, and so I was familiar with its location. It's far more innocuous looking than one might expect, though - obviously I hadn't anticipated a 'Secret Services Workplace – This Way!' road-sign, but it was quite an impressive old building, the complete opposite of Six's sleek base at Vauxhall Cross that I was familiar with. I abandoned the chill of the morning breeze and paced to the entrance, my appreciation of central heating instantly renewed as I stepped inside.

"Rosalind Myers," I had drawled to the security guard.

"Please surrender your bag and mobile phone for a security check," he told me efficiently.

"Is this charade really necessary?" I asked bluntly. Dealing with pushy officials is not my favourite pastime.

"If you have any weapons, I'm asking you to surrender them now," he told me in a very stern and supposedly intimidating voice. Did he honestly believe that I'd waltz into MI5 to kill a senior officer in the library with a candlestick? His ridiculously formal conduct suggested so, to the point that I considered dealing the 'don't you know who I am?' card before an interruption presented itself.

"Morning, Zaf," the other security guard called to the young man practically bounding through the doors.

"Hey, John. Long time no see. How's the missus?" He fished his ID out of his pocket and grinned.

"Oh, not too bad. Good to see you – it's a relief not to deal with ruffians all the time, mate." He cast a disapproving eye in my direction and I pointedly glared at him and his companion. Their casual use of nicknames was irritating, as was the fact that 'John' wasn't bothering to tend to his work duties. 'Zaf' appeared to be one of those insufferable types who knew just about everyone, and slathered enthusiasm and warmness on every victim that crossed his eye line. Warm, chirpy and cheeky, he was synonymous to an unruly terrier rather than a bloody MI5 officer.

"Wouldn't be so sure I'm not a ruffian, my friend," the terrier replied. "Harry Pearce used that exact phrase in reference to me after I nicked some post-its off his desk."

Harry Pearce. Oh, super. This sparky chap worked in the same section that I was about to join and his gaze had just moved my way, almost definitely catching my eye-roll.

"Erm, I'll leave you to it, pal," he chirped. "Enjoy the day." He sauntered over to my direction.

"Morning, Gary. Trouble?"

"Nothing I can't handle," the guard growled, finally letting the two brain cells he possessed cooperate as he passed my bag through the scanner.

"I can vouch for this lady, Gary. This is Ros Myers. New recruit to my Section. Shall I escort her up?"

Lady? Escort? The terrier suddenly seemed to be plucking phrases from an aristocratic gent in a 19th century novel. I wanted to tell him exactly where he could shove his chivalry but bit my tongue. This hadn't turned out to be the no-nonsense start to the term that I had hoped for. Being challenged by authority was something I'd always struggled with, from parents to teachers to bossy peers, and the fact that I would already be regarded with contempt following my father's actions wouldn't help matters.

"She needs ID," Gary spelled out. The terrier cocked his head to the side characteristically and smiled.

"Of course," he cooed. "Harry Pearce would be able to verbally assure you – shall I get him on the phone?"

Gary's features tightened. "Won't be necessary," he grumbled, waving us through. I noted with interest that using Harry's name seemed to work magic around here – a trick that I would be sure to utilise.

"I'm Zaf," the terrier yapped at my heels.

I didn't bother replying.

"Do you want me to show you around sometime, Ros?"

I turned on my heel. "I wasn't aware that this was a bloody middle school induction day, Zaf."

He frowned slightly. "Okay. Have it your own way." He made his way to the lift and prodded a button, the doors snapping shut.

Shit. Marching onto the Grid with no idea where I was supposed to sit or what work I was supposed to complete could be hideously embarrassing. Plus, the humiliation of my father's betrayal had made me bitter, my defence mechanism of cruel quips coming into play more often, and so it was unlikely that I'd make any chums to show me the ropes.

Also, I was not elated at the idea of seeing Adam Carter again, seeing as the last time I had encountered him had resulted in me crying, fully and humiliatingly. The more I think about it, the more horrified I feel. At first I tried to cut myself some slack – the fate of my father was about to tear my family apart – but I should have handled the situation better. If crying had been absolutely necessary, I should have at least had the decency to do it in private.

As I impatiently waited for the lift to return I pulled out my phone, scrolling through the contacts. He was saved under Daddy because I previously adored and respected him. Now it seemed pathetic and childish, and I could hear Adam's voice mocking me, calling me 'daddy's little girl.' I removed the name, ready to re-enter with 'Father' before realising it didn't matter. I efficiently clicked delete.

"Good morning," someone said suddenly: Harry. He was smiling, one eyebrow raised.

"Not lost already, I hope?" He spoke gently but the tiny knowing smile he shot felt patronising enough for me to summon a cold reply.

"Nope. Just checking I've got the relevant phone numbers for the new job. Three nine's for danger, isn't it?" I dropped my phone into my bag and met his gaze with a sardonic smile.

Harry looked somewhat bewildered at my response, pressing the lift button again and studying the floor. Perhaps he thought I would be a completely submissive officer, humbled by my run-in with the law and quietened by the speculations about my father's imprisonment.

But if anything, the last few weeks have renewed my determination to prove myself.

...

My desk was close to the ter- Zaf's. A tiny chip of a conscience instructed that I should apologise – it had the voice of my childhood friend, Miranda. She was a right goody-goody two shoes with the posh voice and mummy and daddy to prove it – then again, I did too, but with a streak of recklessness thrown into the gene pool. Still, I had usually been able to coax her into trouble and likewise she had made an indelible impression on my own morals, despite my insistence to suppress her influence. My own arrogance and stubbornness ensure that I want to make my own decisions all the time with no outside help, and making new friends was so low down on my priorities list that it wasn't even worth mentioning. But if I wanted to be successful in this workplace, I would have to strike up alliances. These people are well connected, well trained and clever – they may well be useful to me later in life. I had been unnecessarily dismissive of Zaf's offer of help, despite being genuinely appreciative of it.

"I was out of order." The words felt wooden and lacked any real sincerity. Zaf dragged his eyes from the computer screen to my face and he raised his eyebrows.

"I was short with you earlier." I coughed. This was thoroughly uncomfortable – I decided to brazen it out. "I don't want any bad feeling seeing as we're going to be working together. I'd rather be professional. Touché?"

That tiny trademark smile made its way onto his mouth. "Touché, Ros."

"And if that offer of a guided tour still stands, I'd appreciate it," I added, even conjuring up a small smile. Being the new girl and being looked down on was a poisonous enough combination without the addition of wandering around Thames House like a headless chicken. I wanted to get to grips with my new workplace as soon as possible, and having someone to assist me in achieving that objective would be advantageous.

"It's a date," Zaf responded with a wink, to which I responded with an eye roll. "Welcome to the Grid," he grinned.

"Glad to be on board," I replied, watching him gather papers in his arms and head through a set of doors veering off from the main work area.

I promptly located the predictably crummy office kitchen and made myself a piping mug of coffee. The gaudy neon smiley face clock on the wall (which I prayed was purchased either ironically or drunkenly) told me that it was just approaching nine. I wondered of the whereabouts of other colleagues – I anticipated that my mysterious recruiter Adam would put in an appearance sooner or later. He seemed the happy-go-lucky type but with the skill and charm of an intelligence officer drummed into his bones. At this hour he was probably still asleep in an anonymous hotel with a female in tow, same clothes chucked over a chair somewhere and with no grooming other than a hand scraped through the hair in order to fashion himself into an attractive spy.

He's not James bloody Bond, Myers, and you don't do speculation, I scolded myself. Then again, it was always somewhat amusing to suss people out beforehand and then watch my imaginations play out before my very eyes. I've always been spookily accurate at judging a person's character.

The thud of footsteps broke my trance as an older man paced into the kitchen and flicked on the kettle, his eyes fixed on the floor. I recognised him from my second visit to the Grid – he was providing evidence of my father's betrayal, but I didn't know his name. For a brief moment I thought of introducing myself before realising I wasn't exactly the chatty, girl-guide type, and he of course knew exactly who I was. I highly suspected that his obvious grief stemmed from the murder of one of their colleagues; an unfortunate repercussion of the plot I got entangled in, and so it would be inappropriate of me to offer my condolences. I left the kitchen and plunked my coffee on my desk, rigging up the computer before me.

...

My first day had passed without any serious setbacks, although Gary the security guard shot me a particularly vitriolic look on my way out in the evening. The team were close-knit, as Harry had said, to the point of mild annoyance. There wasn't a second where they weren't offering to make a round of tea or calling out each other's first names as a way of summoning or asking if anyone needed a lift home. I almost wished for some atrocity to happen just so they'd all snap back into chilling efficiency.

As for the team members individually, I had worked with worse. Harry was the boss and no-one seemed to question his judgement. He was wise, but knew when to bend the rules a little, which make me respect him. Too often are bosses snooty and detached from their team – Harry was the polar opposite.

Zaf was the typical office joker who was probably born seeking female attention and completely blind to the fact that not every woman fell head over heels for his alleged 'charms'. That said, he was quick-witted and clearly a skilled officer. I would forgive his flirtatiousness: for now. He had also been the first person to attempt to befriend me, and despite our slightly shaky start I could tell that he was a decent guy whose company I wouldn't resent.

Ruth Evershed was a middle-aged, fiercely loyal and ridiculously intelligent analyst with enough of what I call 'moral maturity' to rile me. She seemed to be the team member who injected lethal amounts of humanity into the operation, always looking out for the underdog and the first to call someone up on their lack of regard for individual lives. My stance has always been of the greater good, which doesn't make me heartless but operationally focussed enough to realise that you have to consider the most favourable outcome for the masses. She had been taunting me with Adam during the coup, talking about my father's link to the Russian mafia and his involvement in the plane crash, and so I naturally wanted as little to do with her as possible. I imagine we have little in common anyway, perhaps other than shopping at the same coat shop. It was also blatantly obvious that she harboured an irrevocable affection for Harry, although I doubt she has sufficient courage to act upon her feelings.

Joanna Portman was suitably naive for a junior officer and was obviously bright but lacked enough backbone for my liking. I assumed she was new to the role of a spy but she was clearly appreciated by her other workers, an affection she returned abundantly. She doted on Adam and his effortless skill, chatted with Ruth on coffee breaks, offered to help Malcolm with surveillance. Her respect for Harry was evident and she was the only one who didn't rebuff Zaf's flirtatiousness with a sarcastic comment or withering look. Jo was the girl that everyone wanted to be friends with, which automatically made her someone that I wanted to avoid.

The miserable man I had encountered in the kitchen was Malcolm, best friend of the murdered colleague. He was the techie, which meant I thankfully wouldn't have to associate with him much, but it appeared that he was humble but scarily intelligent with a heart bigger than Harry's ostentatious leather desk chair.

Adam, however much it pained me to admit, I had got completely wrong. One of Jo's merits was her loose tongue; it was a generally annoying trait, but her chattiness paid off in discovering more about my new colleagues. Adam had been the happy-go-lucky charmer once upon a time, but his wife had been killed little under a year ago and he had since been struggling to come to terms with her death. He was now a single parent battling personal traumas as well as professional difficulties. When Jo told me all of this I almost felt pity for him: as sob stories go, it was a particularly vicious one. Then again, Adam was still living and breathing and working for the Service, so he must be dealing with his emotions in one way or another with a relative degree of success.

However, he'd tried to be chatty. Lethal mistake. He even asked how I was 'generally' following my crying session. I made it perfectly clear that approaching the topic again would most likely result in me battering him to death with my lever arch folder.

At least I'd now be able to get my teeth into some proper work - Zaf had been sent undercover to set Operation Waterfall in motion and we'd need sufficient time to get him trusted and in the right group. I usually loathe waiting but in this scenario I was thankful – it gave me ample opportunity to play catch-up and so when Adam started mentioning Waterfall mysteriously I had the upper hand. Those next few weeks had also allowed me to slip under the radar a little. It seemed I'd disposed of my sign spelling out 'Traitor' fastened like rope around my neck and was finally just seen as one of them, albeit the moody one who goes to the roof at lunchtimes and takes her coffee black, and no she wouldn't like a bloody chocolate digestive.

Zaf was now well and truly accepted as a team member of the terrorist cell we had infiltrated and it had been a textbook operation until the ringleader shot dead an innocent. Ruth suggested it was an attempt to flush out infiltrators and I felt momentarily uneasy. Of course, they had dealt with previous similar operations and had sufficiently backstopped Zaf's legend which he'd learnt off by heart, but the thing about rogues and miscreants and terrorists is that they're unpredictable. If they weren't, we'd be able to intervene and stop them. But the opposition is often a lot cleverer these days, and so MI5 have to step up their game.

I hadn't been watching the screens of the CCTV at the warehouse but was close enough to eavesdrop. Zaf had valiantly attempted to save the other man's life without getting himself killed, but the ringleader Hanif hadn't hesitated to put a bullet in the head of the environmental worker whom he'd murdered just to prove a point. Unfortunately, people all too often find it necessary to spell out a point in blood.

After the potential fiasco had been averted, Zaf and his new friends sloped off to the flat and Jo helpfully spelled out the operation for me in the Meeting Room. It appeared that Adam didn't anticipate that I had common sense enough to do some legwork regarding the current operation on which I would be working. I made it quite clear to Jo that I was well aware of the homework and would be more than capable of completing it, and then she delegated me the task of babysitting Zaf. That stung. I have done something a little more senior. Taking status reports from an agent in the field is obviously a pivotal part of any operation, but something that Jo was more than capable of. Why was I being given the tasks that a junior officer could easily handle? Then again, I hadn't been informed of any official ranking and so it appeared I would have to prove myself before being given any more arduous operational responsibilities. I hit a nerve when enquiring why Jo herself couldn't babysit her little friend and now suspect another potential office romance brewing, God help me.

At least meeting Zaf would give me the opportunity to get out of the Grid and avoid Adam's attempts at niceties. He was obviously trying to patch up our somewhat severed relationship following my father's treason and the tacky seduction routine I had carried out, including the unfortunate coincidence that I wear the same perfume as his dead wife. He didn't believe me that it was a mere coincidence, of course, and although I can't deny that it significantly aided my get-out clause I wouldn't have done something so vulgar. Despite my relief that he finally seemed to have accepted the idea that I didn't intentionally drag up memories of his beloved wife, I was utterly uninterested in associating with Adam on anything other than work matters. I would attempt to be civil, but he was making it rather bloody difficult at the moment.

...

Zaf definitely looked worse for wear. It would have been tough for him to watch that guy get his brains blown out and then have to sit and smile with the people responsible, but he'd been thoroughly professional about the whole thing, even telling me his cover was still intact when I had been enquiring about his personal wellbeing. I tried to push the topic to show I actually cared but he swiftly moved onto operational details. I threw him a bone and allowed his choice of conversation.

Our chit-chat was two minutes at most, but that was substantial time for me to make my judgements. Bright, attentive and quick-witted, Zaf certainly knew what he was doing. Trouble was, this bunch was nasty and their plans were advancing a little too quickly for our liking.

I swept away after telling Zaf that he did the right thing, leaving him to head back to the flat. It was a crummy place and he'd had to neglect his fondness for dressing sharply with considerable distress, but it was clear that he flourished in undercover work. Even I, trained to spot the mistakes of others, couldn't fault his performance. Any intelligence officer worth their salt possesses some acting ability, but some are considerably better than others.

I was then tasked with bringing in and questioning our main man Michael's ex-fiancée, Leigh Bennett. It was evident from the start that she was an intelligent young woman, with guts enough to pull off a little undercover work combined with the necessary looks and charm to win back her old flame. It would have run like clockwork had she not disobeyed my orders to avoid the flat. She was stabbed to death by a suspicious flatmate, whom Michael promptly beat the shit out of before cradling Leigh's body, a suspected terrorist reduced to a broken man through the bloodshed of someone he loved.

In the midst of all that, Jo got herself attacked by a brute called Iain Kallis who was involved in the sale of the thermobaric bomb. She had been playing along well until she made excuses to leave and he slapped her round the face, before attempting to strangle her. Adam and I had found her before Kallis snapped her neck: she looked traumatised but would recover. I thought the fact that I saved her life would mean that she treated me a little better, but she was being annoyingly sensitive about Leigh Bennett, blaming me for making a wrong call for using her. Ultimately, it was not the wrong call – she got us vital intelligence and earned the trust of Michael which Zaf could later use. It was regrettable that this caused a civilian casualty, but sometimes it happens. I'm not emotionally incontinent, but nor do I lack genuine feeling. I've just had enough experience not to cry over the deceased any more.

Zaf came back to the Grid late last night, looking exhausted and in need of a decent shower. When I told him as much, he conjured up a small smile.

I'm glad that he didn't end up stabbed, or shot, or blown to smithereens. As colleagues go, he's a decent one.

...

A/N: I played with the timeline of this a little – I wanted to explore Ros' integration to the team before moving onto Operation Waterfall instead of having that as her first day as seen on screen. 'In the library with a candlestick' is a reference to the detective game 'Cluedo' - potentially a favourite board game of the Spooks! If you have a minute, a review would be very welcome :)