A/N – Thanks again to my faithful readers and reviewers – you know who you are! Just kicking things up a notch here…

The ballroom has not changed much since Havensworth was built; it is still a finely proportioned room with French windows opening to a paved terrace, old crystal chandeliers rewired for modern electricity, a musicians' gallery (currently occupied by a string quartet), an array of balloon-backed chairs and little tables scattered along the walls, and at the far end, a long mahogany bar, which is currently the focal point for most of the men, and not a few women, in the room. I can sense Ruth's nervousness and excitement as we enter the room, and then the attention of others turning upon us momentarily. I stand a little taller, feeling as proud as a lord to have her on my arm, and sweep the room with a casual, yet all-encompassing glance. Who else is here, and should I be worried, are the two questions uppermost in my mind, as I assess men, all looking oddly alike in white tie, and elegantly turned out women. I recognise several operatives from Six, a smattering of GCHQ types, clustered together by the bar, a few people from other sections within Five, most of whom won't know us by sight, and a number of politicos that I immediately determine to avoid at all costs. Then there are the various plus-ones, none of whom I have ever seen before, nor ever expect to see again.

The room is filled with the low buzz of people chattering and laughing, the chink of glasses and lovely, lilting music – Strauss' Tales from the Vienna Woods, if memory serves. It looks like any of a hundred other Midsummer balls taking place across the country tonight, except for the guests. On the surface, they are enjoying themselves like any convocation of men in penguin suits and women in evening gowns; they talk, they drink, some of them are trundling around the dance floor with varying degrees of competency, and from the far corner guffaws of male laughter pinpoint the location of a raconteur holding court. But there the similarities with other social gatherings end.

There is a frisson in the air, barely detectable unless one is a highly trained surveillance officer or field agent: the crackle and hum of intelligence on the move as it is gathered, traded, shared, tucked away for future reference…covert glances, tiny signals telegraphed across the room, talk in dark alcoves, ears inclined to overhear conversations not meant to be shared. To my trained eye, it seems that everyone at Havensworth is running an operation tonight, and for a moment I feel queasy with nerves; and then I feel Ruth's hand tighten on my arm, and I realise she is just as nervous. Somehow, just knowing that she feels the same way is enough to dissipate the sense of foreboding which has come over me, and I lead her to one of the small, marble-topped tables against the wall, sufficiently secluded that we are able to talk without fear of being overheard. Ruth settles at the table while I fetch drinks – champagne for her, red wine for me – and wend my way back. I begin to appreciate Harry's comparison to a pit of vipers as I make my way through the glittering, noisy throng, and can't help but wonder why Ruth has set her heart on tonight. This world of superficial chatter and shifting shadows, where nothing is quite as it seems, sets my teeth on edge; but she seems to be drinking it all in, eyes shining with excitement as she surveys the room from the safe haven of our table.

As I set our drinks down, Ruth excuses herself, and glides in the direction of the ladies' room. I hope she is tough enough to make it back in one piece – I can't think of anything more terrifying than a gathering of female spooks at close quarters. Still, Ruth has an admirable degree of self-possession, and a chameleon-like ability to fade into the background – although given the way she looks tonight, I doubt that deploying her usual evasive strategy is an option. As I sit, waiting for her, I take the opportunity to conduct a secondary situation analysis, and plan exit strategies if needed. I remember Harry once told me, not long after I had joined, that the surest sign of an old spy is to take note of where they sit in a room; back against the wall, facing the entrance, is the preferred position, all the better to conduct reconnaissance.

Whether subconsciously or not, this is the exact location I have chosen for us…after a few minutes have passed, I begin to cast an anxious eye about the room, trying to see if Ruth has already emerged. Just as I am beginning to contemplate getting up to look for her, she reappears, hastening towards me, smiling, and carrying a plate piled high with food. "I'm so sorry, the queue in the Ladies' was ridiculous, and then it occurred to me that I was starving, so I stopped by the buffet and picked up something for us to eat," she begins, setting the plate down on the table between us. Smoked salmon canapés, bread rolls with butter, some slices of rare roast beef rolled around horseradish cream, and Coronation chicken in lettuce leaf cups – typical summer buffet fare, but nicely done, and I realise that I, too, am hungry – and not just for food…I am suddenly very glad that I have had the foresight to book a room upstairs for the night.

After we have eaten, we sit back and watch the room for a while, Ruth commenting on that woman's dress or speculating on the identity of this man. She recognises a few people by sight, people she has met fleetingly at security briefings or seen operational files for, but so far, no one seems to have noticed us at all, other than the waiters who clear our glasses. We are each on our third drink, and I am feeling relaxed and more confident than usual, when the quartet strikes up the Emperor Waltz, and the next thing I know, Ruth is pulling me to my feet. "Come on! I want to see if all the toe-treading was worth it…" and before I can protest, she is leading me to the dance floor. There are quite a few couples taking a turn; some are professional operatives, working on their seduction skills, while others, by the way they move together, are long term partners. We find a clear space and join the other dancers; there is not enough room for the flying steps of the Viennese waltz, so I begin a slow waltz with Ruth, instead. At first she giggles as she missteps, but while Grandmamma might have taught me how to dance, my father, tall and graceful, taught me how to lead, and it's not long before we are moving nicely around the floor, Ruth proving to be a quick learner in this as in everything else she does.

Our bodies, which are becoming accustomed to fitting together in other ways, soon grow used to this new one-two-three movement, and as we dance I am able to concentrate more on how I am feeling, and less on our footwork. And how I am feeling, quite frankly, is spectacular. To have Ruth in my arms like this is wonderful, and I become aware that some of the other couples have stopped dancing to watch us. I add a couple of flourishes as the floor thins out, and Ruth is smiling at me, her diamond pendant winking in the chandeliers' light, as we swing around and around. Finally, the music ends, and with a little bow, I lead Ruth from the floor to a smattering of light applause, both of us blushing with pleasure and embarrassment at being the unaccustomed centre of attention. We make our way back to our table, before I have to excuse myself, leaving Ruth sitting happily people-watching, her eyes flitting occasionally towards the entrance to the ballroom. As I leave her, it seems to me that she has a faintly expectant air, almost as if she is waiting for someone…Don't be so silly, I chide myself. She's here with me, isn't she?

When I come back a few minutes later, it is to an empty table, but I do not worry unduly…until I see where she is, and worse, who she is with. Somehow, I hadn't spotted him before, even from my prime surveillance position; how long has he been here, and what has he seen? Panicked thoughts skitter through my mind as I struggle to make sense of the scene before my appalled eyes. The hairs on the back of my neck rise, and I feel ill, my breathing suddenly tightening as my diaphragm tenses; can it be that Ruth is actually dancing with him…how could she? Oh, Ruth…