Travellers in the Arab countries have often remarked on the way a native will position his face disconcertingly close during conversation. This, of course, is simply a local custom that happens to differ from our own, and any open-minded visitor will before long come to think nothing of it. It has occurred to me that I should try and view in a similar spirit something which, over these three weeks I have been here in Shanghai, has come to be a perennial source of irritation: namely, the way people here seem determined at every opportunity to block one's view. No sooner has one entered a room or stepped out from a car than someone or other will have smilingly placed himself right within one's line of vision, preventing the most basic perusal of one's surroundings. Often as not, the offending person is one's very host or guide of that moment; but should there be any lapse in this quarter, there is never a shortage of bystanders eager to make good the shortcoming. As far as I can ascertian, all the national groups that make up the community here – English, Chinese, French, American, Japanese, Russian – subscribe to this practice with equal zeal, and the inescapable conclusion is that this custom is one that has grown up uniquely here within Shanghai's International Settlement, cutting across all barriers of race and class.

It took me a good few days to put my finger on this local eccentricity, and to appreciate that it was what lay at the root of the disorientation which threatened to overwhelm me for a time upon first arriving here. Now, although I still find myself occasionally annoyed by it, it is not a thing of undue concern. Besides, I have discovered a second, complementary Shanghai practice to make life a little easier: it appears to be quite permissible here to employ surprisingly rough shoves to get people out of one's way. Though I have not yet found the nerve to take advantage of this licence myself, I have already witnessed on a number of occasions refined ladies at society gatherings giving the most peremptory pushes without provoking as much as a murmur.

When on my second night here I entered the ballroom on the penthouse floor of the Palace Hotel, I had yet to identify either of these curious practices, and consequently found much of that evening undermined by my frustration with what I then took to be the inordinately crowded nature of the International Settlement. Stepping out of the lift, I had barely glimpsed the plush carpet leading into the ballroom – a row of Chinese doormen lined all along it – when one of my hosts for the evening, Mr MacDonald from the British consulate, put his broad frame before me. As we strode on towards the doorway, I noticed the rather charming way each doorman, as we passed, would bow and bring his white-gloved hands up together. But we were hardly past the third man – there were probably six or seven in all – when even this view was obstructed by my other host, a certain Mr Grayson, representing the Shanghai Municipal Council, who stepped up beside me to continue whatever he had been saying during our ascent in the lift. And I had no sooner entered the room in which, according to my two hosts, we were to witness ‘the city's smartest cabaret and a gathering of Shanghai's elite’ than I found myself in the midst of a drifting crowd. The tall ceilings above me, with their elaborate chandeliers, led me to suppose the dimensions of the room were pretty vast, though for some time I had no way to corroborate this. As I followed my hosts through the throng, I saw large windows all along one side of the room through which, at that moment, the sunset was streaming in. I glimpsed too a stage at the far end, upon which several musicians in white tuxedos were wandering about talking. They, like everyone else, appeared to be waiting for something – perhaps simply for night to fall. In general there was a restlessness, with people pushing and circling one another to no clear purpose.

I almost lost sight of my hosts, but then saw MacDonald beckoning to me, and I eventually found myself sitting down at a small table with a starchy white cover to which my companions had pushed their way. From this lower vantage point I could see that in fact a large expanse of floor had been left vacant – presumably for the cabaret – and that almost all present had squeezed themselves into a relatively narrow strip along the glazed side of the room. The table we were sitting at was part of a long row, though when I tried to see how far the row extended, I was once again thwarted. No one was sitting at the tables immediately neighbouring ours, probably because the jostling crowd made it impractical to do so. Indeed, before long, our table came to feel like a tiny boat assailed on all sides by the tides of Shanghai high society. My arrival, moreover, had not gone unnoticed; I could hear murmurs spreading around me conveying the news, and more and more gazes turned our way.

In spite of all this, until things grew quite impossible, I recall trying to continue the conversation I had started with my hosts in the car bringing us to the Palace Hotel. At one point I remember I was saying to MacDonald:

‘I very much appreciate your suggestion, sir. But in truth, I'm happy to pursue my lines of enquiry alone. It's how I'm accustomed to working.’

‘As you will, old fellow,’ MacDonald said. ‘Just thought I'd mention it. Some of these fellows I'm talking of, they certainly know their way about this city. And the best of them are as good as anything you'll find at Scotland Yard. Just thought they might save you, all of us, some valuable time.’

‘But you'll recall my telling you, Mr MacDonald. I left England only once I'd formed a clear view of this case. In other words, my arrival here isn't a starting point, but the culmination of many years’ work.’

‘In other words,’ Grayson suddenly put in, ‘you've come here to us in order to tie up the case once and for all. How marvellous! It's wonderful news!’

MacDonald gave the Municipal Council man a disdainful glance, then continued as though the latter had not spoken.

‘I don't mean to cast any doubt upon your abilities, old fellow. Your record speaks for itself, after all. I was only suggesting a little back-up in the way of personnel. Strictly under your command, naturally. Just, you know, to quicken things up. Having only just got here, it mightn't be so clear how urgent our situation's become now. It all looks pretty relaxed here, I know. But I rather fear we don't have a great deal of time left.’

‘I fully appreciate the urgency, Mr MacDonald. But I can only say again, I've every reason to believe things will be brought to a satisfactory conclusion in a relatively short time. Provided, that is, I'm allowed to go about my enquiries unhindered.’

‘That's splendid news!’ Grayson exclaimed, earning another cold look from MacDonald.

For much of the time I had been in his company that day, I had been growing increasingly impatient with MacDonald's pretence at being nothing more than a consulate official charged with protocol matters. It was not just his inordinate curiosity concerning my plans – or his eagerness to foist ‘assistants’ on me – that gave him away; it was the air of refined duplicity he carried along with his languid, well-bred manners that marked him out so readily as a senior intelligence man. By that point in the evening, I must have grown weary of humouring him in his charade, for I put my request to him as though the truth had been acknowledged between us long before.

‘Since we're on the question of assistance, Mr MacDonald,’ I said to him, ‘there is in fact something you might be able to do for me that would be of immense help.’

‘Try me, old fellow.’

‘As I mentioned before, I have a particular interest in what I believe the police forces here are calling the Yellow Snake killings.’

‘Oh yes?’ I could see a guardedness falling over MacDonald's face. Grayson, on the other hand, seemed not to know to what I was referring, and looked from one to the other of us.

‘In fact’ – I went on, looking carefully at MacDonald – ‘it was when I'd gathered sufficient evidence on these so-called Yellow Snake killings that I made the decision finally to come here.’

‘I see. So you're interested in the Yellow Snake business.’ MacDonald glanced about the room nonchalantly. ‘Nasty affair. But not all that significant, I wouldn't have thought, in terms of the larger picture.’

‘On the contrary. I believe it to be highly relevant.’

‘I'm so sorry,’ Grayson managed finally to put in. ‘But just what are these Yellow Snake killings? I've never heard of them.’

‘It's what people are calling these communist reprisals,’ MacDonald told him. ‘Reds murdering relatives of one of their number who's turned informer on them.’ Then he said to me: ‘We get this happening from time to time. The Reds are savages in such matters. But it's a matter between the Chinese. Chiang Kai-shek's well on top of the Reds and plans to stay that way, Japanese or no Japanese. We try to keep above it, you know. Surprised you're so interested in all that, old fellow.’

‘But this particular set of reprisals,’ I said, ‘these Yellow Snake killings. They've been continuing for a long time. Off and on for the last four years. During which time thirteen people have to date been murdered.’

‘You'll know the details better than me, old fellow. But from what I've heard, the reason the reprisals are protracted is that the Reds don't know who their traitor is. They began by slaughtering the wrong people. A little approximate, you see, this Bolshevik vision of justice. Every time they change their ideas about who this Yellow Snake chap might be, they go out and slaughter another family.’

‘It would help things greatly, Mr MacDonald, if I were able to speak to this informer. The man referred to as the Yellow Snake.’

MacDonald shrugged. ‘That's all between the Chinese, old fellow. None of us even know who this Yellow Snake is. In my view, the Chinese government would do well to announce his identity before more innocent people get mistaken for his relatives. But honestly, old fellow. It's all between the Chinese. Best leave it that way.’

‘It's important I get to speak to the informer.’

‘Well, since you feel so strongly about it, I'll have a word with a few people. But I can't promise much. This chap seems pretty useful to the government. Chiang's men keep him pretty well under wraps, I'd imagine.’

I had become aware by this point of ever more people pressing in on all sides, eager not just to glimpse me in the flesh, but to overhear something of our conversation. In such circumstances, I could hardly expect MacDonald to talk frankly, and I decided I should abandon the matter for the time being. In fact, I was overcome at that moment by a strong urge to rise and get a little air, but before I could move, Grayson had leant forward with a cheerful smile, saying:

‘Mr Banks, I appreciate this might not be the best time. But I wanted just to have a quick word. You see, sir, I've been charged with the happy task of organising the ceremony. That's to say, the welcoming ceremony.’

‘Mr Grayson, I don't wish to seem ungrateful, but as Mr MacDonald here just put it, time is rather pressing. And I feel I've been welcomed already with so much lavish hospitality …’

‘No, no, sir’ – Grayson laughed nervously – ‘I was referring to the welcoming ceremony. I mean, the one welcoming back your parents after their years of captivity.’

This, I admit, rather took me by surprise and perhaps for a second I just stared at him. He let out another nervous laugh and said:

‘Of course, it's somewhat jumping ahead, I realise. You've first to do your work. And of course, I don't wish to tempt fate. All the same, you see, we are obliged to prepare. As soon as you announce the solving of the case, everyone will look to us, the Municipal Council, to provide an occasion worthy of such a moment. They'll want a pretty special event, and they'll want it promptly. But you see, sir, to organise something on the scale we're talking of, it's no simple matter. So you see, I wondered if I could put a few very basic options before you. My first question, sir, before anything else, is if you're happy with the choice of Jessfield Park for the ceremony? We will, you see, require substantial space …’

While Grayson had been speaking, I had become steadily aware of the sound – from somewhere behind the hubbub of the crowd – of distant gunfire. But now Grayson's words were suddenly cut off by a loud boom which shook the room. I looked up in alarm, only to see all around me people smiling, even laughing, their cocktail glasses still in their hands. After a moment, I could discern a movement in the crowd towards the windows, rather as though a cricket match had resumed outside. I decided to seize the opportunity to leave the table, and rising, joined the drift. There were too many people in front of me to see anything, and I was trying to edge my way forward when I became aware that a grey-haired lady by my shoulder was talking to me.

‘Mr Banks,’ she was saying, ‘do you have any idea at all how relieved we all feel now that you're finally with us? Of course, we didn't like to show it, but we were getting extremely concerned about, well’ – she gestured towards the sound of gunfire – ‘my husband, he insists the Japanese will never dare attack the International Settlement. But then you know, he says it at least twenty times a day, and that's hardly reassuring. I tell you, Mr Banks, when news of your impending arrival reached us, that was the first good news we'd had here in months. My husband even stopped repeating that little mantra of his about the Japanese, stopped for at least a few days. Good heavens!’

Another thunderous explosion had rocked the room, provoking a few ironic cheers. I then noticed that a little way in front of me, some French windows had been opened, and people had pushed out on to a balcony.

‘Don't worry, Mr Banks,’ a young man said, grasping my elbow. ‘There's no chance of any of that coming over here. Both sides are extremely careful now after Bloody Monday.’

‘But where's it coming from?’ I asked him.

‘Oh, it's the Jap warship in the harbour. The shells actually arc over us and land over there across the creek. After dark, it's quite a sight. Rather like watching shooting stars.’

‘And what if a shell falls short?’

Not only the young man I was talking to, but several others around me laughed at this idea – I thought rather too loudly. Then another voice said:

‘We'll have to trust the Japs to get it right. After all, if they get sloppy, they're just as likely to drop one behind their own lines.’

‘Mr Banks, would you care for these?’

Someone was holding out a pair of opera glasses. When I took hold of them, it was as if I had given a signal. The crowd parted before me, and I found myself virtually conveyed towards the open French windows.

I stepped out on to a small balcony. I could feel a warm breeze and the sky was a deep pink. I was looking down from a considerable height, and the canal was visible past the next row of buildings. Beyond the water was a mass of shacks and rubble out of which a column of grey smoke was rising into the evening sky.

I put the glasses to my eyes, but the focus was entirely wrong for me and I could see nothing. When I fiddled with the wheel, I found myself gazing on to the canal, where I was faintly surprised to see various boats still going about their normal business right next to the fighting. I picked out one particular boat – a barge-like vessel with a lone oarsman – that was so piled up with crates and bundles it seemed impossible for it to pass under the low canal bridge just beneath me. As I watched, the vessel approached the bridge rapidly, and I was sure I would see at least a crate or two fall from the top of the pile into the water. For the next few seconds, I went on staring through the glasses at the boat, having quite forgotten the fighting. I noted with interest the boatman, who like me was utterly absorbed by the fate of his cargo and oblivious of the war not sixty yards to his right. Then the boat had vanished under the bridge, and when I saw it glide gracefully out the other side, the precarious bundles still intact, I lowered the glasses with a sigh.

I realised a large crowd had been gathering at my back while I had been looking on to the canal. I handed the glasses to someone nearby and said to no one in particular: ‘So that's the war. Most interesting. Are there many casualties, do you suppose?’

This set off a lot of talking. A voice said: ‘Plenty of death over there in Chapei. But the Japs will have it in a few more days and it'll go quiet again.’

‘Wouldn't be so sure,’ someone else said. ‘The Kuomintang's surprised everyone so far, and my bet is they'll keep doing so. I'd bet on them holding out a good while yet.’

Then everyone around me seemed to start arguing at once. A few days, a few weeks, what difference did it make? The Chinese would have to surrender sooner or later, so why did they not do so now? To which several voices objected that the conclusion was not nearly so cut and dried. Things were changing by the day, and there were many factors each impinging on the others.

‘And besides,’ someone asked loudly, ‘hasn't Mr Banks turned up?’

This question, obviously intended to be rhetorical, nevertheless hung oddly in the air, causing a hush to fall and all eyes to turn to me once more. In fact, I got the idea that it was not only the immediate group around the balcony, but the entire ballroom that had fallen into silence and was awaiting my response. It struck me that this was as good a time as any to make an announcement – one that perhaps had been called for from the moment I had entered the room – and clearing my throat, I declared loudly:

‘Ladies and gentlemen. I can well see the situation here has grown rather trying. And I have no wish to raise false expectations at such a time. But let me say that I would not be here now if I were not optimistic about my chances of bringing this case, in the very near future, to a happy conclusion. In fact, ladies and gentlemen, I would say I am more than optimistic. I beg then for your patience over this coming week or so. After that, well, let us see what we have achieved.’

As I uttered these last words, the jazz orchestra suddenly started up within the ballroom. I have no idea if this was simply a coincidence, but in any case the effect was to round off my statement rather nicely. I felt the focus of the room shifting away from me, and saw people starting to return inside. I too made my way back into the room, and as I tried to find our table again – I had for a moment lost my bearings somewhat – I noticed that a troupe of dancing girls had taken the floor.

There were perhaps as many as twenty dancers, many of them ‘Eurasians’, dressed skimpily in matching outfits with a bird motif. As the dancers proceeded with their floor show, the room seemed to lose all interest in the battle across the water, though the noises were still clearly audible behind the cheery music. It was as though for these people, one entertainment had finished and another had begun. I felt, not for the first time since arriving in Shanghai, a wave of revulsion towards them. It was not simply the fact of their having failed so dismally over the years to rise to the challenge of the case, of their having allowed matters to slip to the present appalling level with all its huge ramifications. What has quietly shocked me, from the moment of my arrival, is the refusal of everyone here to acknowledge their drastic culpability. During this fortnight I have been here, throughout all my dealings with these citizens, high or low, I have not witnessed – not once – anything that could pass for honest shame. Here, in other words, at the heart of the maelstrom threatening to suck in the whole of the civilised world, is a pathetic conspiracy of denial; a denial of responsibility which has turned in on itself and gone sour, manifesting itself in the sort of pompous defensiveness I have encountered so often. And here they now were, the so-called elite of Shanghai, treating with such contempt the suffering of their Chinese neighbours across the canal.

I was moving along the line of backs that had formed to watch the cabaret, trying to contain my sense of disgust, when I realised someone was tugging on my arm and turned to find Sarah.

‘Christopher,’ she said, ‘I've been trying to get over to you all evening. Have you no time to say hello to your old friends from home? Look, Cecil's over there, he's waving to you.’

It took me a little while to get a view of Sir Cecil through the crowd; he was seated alone at a table in a far corner of the room, and indeed was waving to me. I waved back, then looked at Sarah.

It was our first encounter since my arrival. The impression I received of her that evening was that she seemed very well; the Shanghai sun had removed her customary pallor to some advantage. Moreover, as we exchanged a few friendly words, her manner remained light-hearted and assured. It is only now, after the events of last night, that I find myself thinking over again that first encounter, in an attempt to discover how I could have been so deceived. Perhaps it is only hindsight that makes me recall something overly deliberate in her smile, particularly whenever she mentioned Sir Cecil. And although we exchanged little more than pleasantries, after last night, one phrase she uttered that evening – which even at the time rather puzzled me – has continued to return to me all day.

I had been enquiring how she and Sir Cecil had enjoyed the year they had spent here. She had been assuring me that although Sir Cecil had not achieved the breakthrough he had hoped for, he had none the less done much to earn the gratitude of the community. It was then that I had asked, with nothing much in mind:

‘So then you've no immediate plans to leave Shanghai?’

At which Sarah had laughed, cast another gaze towards Sir Cecil's corner, and said: ‘No, we're quite settled for now. The Metropole's very comfortable. I don't expect we'll be going anywhere in a hurry. Not unless someone comes to the rescue, that is.’

She had said all this – including this last remark about being rescued – as though telling a joke, and although I did not know exactly what she meant, I had responded with a small laugh to go with hers. We had then, as far as I recall, talked about mutual friends in England until Grayson's arrival effectively put an end to a seemingly uncomplicated conversation.

It is only now, as I say, after last night, that I find myself searching back through my various encounters with Sarah over these three weeks, and it is this one phrase, added as a kind of afterthought to her breezy reply, to which I continue to return.