My liaison demanded secrecy, and what better way of ensuring that than to act entirely normally? I might have wandered the streets, soaking up the atmosphere of the place which was already coiling itself around my being. Venice is the most dangerous place on earth, or was then, until the tourists came and swamped the air of threat, which existed in its very stones, with the futile frivolity of the sightseer, and converted the inhabitants into supplicants of the transient.

'Why so moody?' Such might have been the question had any acquaintance encountered me, and it was far too soon to run such risks. So I resolved to shut off that part of my thoughts and switch my attention to other things. There was a part of me – an ever-diminishing, weakening part, it is true – which fought against the seductions of the city, although only half-heartedly.

I walked to the offices of the Banca di Santo Spirito and left my card for Signor Ambrosian. I wished to meet a man who knew about the city – knew how it worked, that is, rather than knew about its buildings, which is always the easiest thing to discover, and who also knew about Macintyre. I have always found it strange that people are willing to travel to a place, and devote some considerable energy to doing so, yet leave with not the slightest knowledge or interest in the lives of the inhabitants.

An old friend of mine travelled through the Balkans a few years ago and spent months in those countries, yet came back knowledgeable only about landscapes and the architecture of Orthodox monasteries. How was capital accumulated? How were the cities run? Was the system of taxation efficient or no? What levels of literacy and discipline could you count on among the population? What, in other words, about the stuff of their lives? Not only did he have no knowledge of these things, he had no interest in them, seeming to think that monasteries merely pop out of the ground like mushrooms without any application of either money or labour, and that cities are simply wished into existence for no reason other than to delight the eye of the visitor.

The same applies to Venice, but on a grander scale. What were these people doing living in the middle of the sea like that? Why, in their days of greatness, did they not migrate to the land? How, now that those days of grandeur were past, did they intend to adapt themselves to a new world? Signor Ambrosian seemed the best fitted to answer such questions. No one else I had yet met was likely to do so.

I wrote a note on the back of my calling card, asking him to send a message to my accommodation, and then returned there for a rest before dinner. I was hungry; the day had been long, and the food not plentiful, and the excitement had worked up a fine appetite in me. I was looking forward to dinner and my own company, for I resolved that that evening I would eat alone. It was natural, even necessary, to place myself in the way of English society, but I was not, that evening, willing to converse with the likes of Longman in a fashion of easy conviviality – and I knew that such a manner was utterly vital if my deception was to be successful. Besides, I was not yet ready to meet Cort again.

For the next few days a certain watchful peace descended on me. All thoughts of leaving and moving on to new sights and places fell away so softly I did not even realise they had departed. I could not even keep myself fixed on reality through business, as I received a letter from Signor Ambrosian's secretary to say the banker was away for a few days, but that he would be happy to make my acquaintance on his return.

I was in love; for the first time in my life, so I thought. When I had taken her, I had abandoned all my caution and any doubts; she was irresistible, and I did not want to resist. Her vulnerability, which hid so well a terrible animality, fascinated me. I could see nothing but perfection. I wanted her more than anything else in my entire life. I was not a passionate man in my habits, not romantic in my behaviour: I imagine this is obvious already. I had disciplined myself carefully and thoroughly, but nature will out; Venice, and Louise Cort broke the dam, and a torrent of emotion burst through. The more I possessed her, the more I was prepared to lose myself in that glorious, unmatched feeling and prove it through recklessness.

I thought I was in love because I knew so little. I thought I loved my wife, but Louise showed me that was mere affection, with not even much respect to solidify it. And then I thought I loved Louise, not realising it was simply passion, untrammelled by knowledge. Only when I came to Elizabeth did I finally understand, and by then I was getting old; it was almost too late. She saved me from a dry and empty life. I had looked for someone perfect, but did not realise until then that was not the point. Only when you can know someone's every fault, failing and weakness and not care do you truly know what love is. Elizabeth certainly has her failings; every single one of them makes me smile with affection, or feel sad for her sufferings. I have known her now for nearly two decades, and every day I know her better, love her more. She is my love and more than that.

But then Louise Cort, the image and remembrance of her, filled my days and my mind, and tinted the city I daily grew to know ever better. I became lover and saviour; my pride and vanity grew as my association with her contrasted my nature all the more powerfully with that of Cort. The practical matters were easily disposed of; there was a man who worked at the hotel I had initially stayed in. Signor Fanzano spoke English and had struck me as a robust, commonsensical fellow, worldly and discreet.

'I have a certain requirement for accommodation,' I said, when I discovered him near the kitchens of the hotel. 'I need some rooms that are comfortable but private.'

He did not ask what I wanted such a thing for, merely applied himself to the matter. 'Do I take it you do not wish anyone to know you have these rooms?' he asked.

'Yes. That is the main necessity.'

'So not in the centre. Not in San Marco. But, presumably, not too far away either.'

'Precisely.'

'Do you have any particular price in mind?'

'None.'

'And how long would you need this for.'

'I do not know. I will happily pay for three months to begin with. They must be furnished and clean.'

He nodded. 'Leave it to me, Mr Stone. I will send a message when I have come up with something.'

Two days later I received a message to apply to a Signora Murtano in a small street close to San Giovanni è Paolo near the Fondamenta Nuova. She turned out to be one of Fanzano's relations (although everyone in Venice seems to be a relation of everyone else) with a sitting room and bedroom to rent in a dingy house which had fallen far from its days of glory, if it had ever had any. But it had a fireplace (wood extra, as usual), a separate entrance and only the cruellest luck might have caused me to encounter anyone I knew as I was entering or leaving. The price was exorbitant, not least because I had decided to give Fanzano a handsome reward both for his dispatch and for his discretion. It was a good bargain, as it turned out: it acquired the loyalty of a man who served me well for the next three decades, but nonetheless, I felt at the time that the price of love in Venice was steep.

Still, it was done, and the day after I had made the arrangement, I arranged for Louise to accompany me on another tour of the city. We visited San Giovanni together, and then I showed her my find.

She knew exactly what I intended as we approached the front door, and I was afraid that the practicality of it might affect her sensibilities. And so it did, but only to make her more wild and passionate.

'Don't open the shutters,' she said, as I moved to let some light into the rooms so she could see it better. We spent the next two hours exploring a new land far more exotic than a mere city of brick and marble could ever be, even if it does float in the ocean like some fading flower.