It was terrifying. I have never in my life been so petrified, and if this disappoints, then I am sorry to disabuse you still further of any notions of heroism. I did not join a banking house to get my head kicked in down some malodorous Parisian alleyway. I was cursing myself and that wretched civil servant for bringing about my presence there. I could have turned on my heel and walked out, the banks of the Seine were scarcely a hundred yards away and there at least was some gas lighting. The bridge to the Ile-de-la-Cité was another few minutes' walk. Even less if you ran in total panic, not caring for your dignity. I did not take this course. Instead, I stopped at every flicker of light coming from an open window and consulted my map, wiping the rain from my eyes, and slowly made my way forward, getting ever close to my destination, keeping all thoughts of what on earth I might find there at the back of my mind. I have always had a stubborn streak in me; it can be a disadvantage, sometimes.

I could not decide whether I was being manfully determined or childishly stupid. I continued until I reached the door on the left that the curt instructions had mentioned. I gently pushed it with my hand. It was not locked. It was hardly on hinges at all, and was kept in place mainly by its own weight as it dragged on the floor and leaned against the door posts. Knocking seemed a little absurd in the circumstances, so I put my shoulder to it and levered it up and forwards until a gap large enough for me to slip through opened up.

The passage inside it was completely dark, and the musty smell of neglect and damp hung about it. I waited to see if my eyes could make something out but the blackness was so total that this accomplished little. Unlike the well-equipped agent of novels, I had no matches. There was no sound except for the patter of rain outside and the chuckle of the water as it ran down the street. The thing I was most aware of was my feet, which were soaking wet and icy cold. As standing feeling frightened and cold accomplished nothing, I gingerly made my way forward, arms out like a blind man, and bumped first into a wall this way, then into another that way. Then I caught something brushing against my sleeve as I turned, and realised I had touched a banister. There was a staircase! Carefully, I put my foot on the first step, thinking to go up quietly. That was useless; the wood gave a crack like a gun going off as my full weight came upon it, so I abandoned all notion of discretion and concentrated simply on not falling, feeling my way up, step by step until I came to a landing. There the stairs ended, and there, on the left, I felt a door. Assuming I was in the right street and the right building (about which I had no confidence whatsoever), I must have arrived at my destination. I listened carefully, but could hear nothing. I knocked; softly at first, then in frustration and annoyance, hammered on the door as loudly as I could.

I heard a low groan after my first knock and the sound of someone falling out of bed after my second, then a muttering. Next a sound like someone being sick, then urinating in a metal pot. The door opened, just a crack at first, then more widely. An oil lamp was held up, its glare preventing me from seeing who was holding it. 'Come in, then,' I heard. A gruff voice, speaking in a mumbling French I could barely understand.

So in I went.

I had never been in a room so filthy or so rank before, and my first instinct was to turn tail and flee. The occupant saw this reaction on my face but, instead of being offended, found it as funny as one can find anything when one is nursing a violent hangover. He was at least dressed, after a fashion, though not shaved and, I guessed, he had not shaved for days, for the grey stubble on his chin – he was a man past fifty – shone in the rays of thin light that came from the smoking lamp he put down on a rickety table.

He was short, broad and powerfully built, stooped over but with lively eyes that never rested long in one place. A deeply lined face, with a thin scar down his left cheek, which was otherwise blotchy from drink and hard living. But despite his surroundings and his gross inelegance, he had a purposeful air, almost one of confidence. All this was communicated in a few seconds and I cannot say that I realised any of this until much later. At that particular moment, the smell and the dirt was all I noticed.

'I've come from Mr Wilkinson for a package,' I said.

'You're the new boy, are you?' he said with the heavy sigh of the deeply disappointed. He had switched to English after he had examined me carefully with those eyes. I noticed that there was the faintest foreign accent to his voice. Not French, certainly, but his original language was so covered over by time and lack of use it was difficult to ascertain what it might have been. 'Do you have something for me?'

'No.'

'No piece of paper, no other letter?'

'No. Why?'

'Because how am I meant to believe you really do come from Mr Wilkinson? You may be working for the French Government, which would not be good for you at all.'

He said it in a quiet fashion which was deeply threatening.

'I can offer you no proof whatsoever,' I replied. 'And I am not sure I would, even were I able to do so.'

'What's your name?'

'Cort,' I replied. 'Henry Cort.'

'A curious name; not very English. Dutch? Flemish?'

I bridled a little at that. 'I can assure you I am thoroughly English,' I said stiffly. 'My father's family arrived in England from the Low Countries to escape persecution, but that was nearly two hundred years ago.'

'And your father is alive?'

'Yes, although he suffers from persistent ill health. My mother is dead.'

I sensed a faint quickening of his interest at this, although there seemed to be nothing behind it. 'And your father's occupation?'

'He is an architect when his health permits. Most of the time he is too frail to work.'

'I see. And you were born in . . .'

'Eighteen sixty-three.'

He leaned back in his chair and stared at the ceiling as he considered this piece of information. Then he leant forward, grabbed my left arm, and pulled up the sleeve of my jacket. Snorted, then banged his knees with his hands and looked up.

'My apologies for the interrogation, although not for the doubts. Unless you become as suspicious as I am, you will not live long in this game.'

'I do not intend to play any game,' I replied. 'Nor do I see how what I have just said can convince you of my honesty.'

He almost smiled at this remark. 'You must allow me to preserve my secrets. But Mr Wilkinson knows what he is doing. He sent no proof of your identity because your very existence is its own proof.'

He stood up. 'Don't look so puzzled. It's of no significance. Have you done this before?'

I didn't understand a word he was talking about. All I knew was that even the dangers of walking alone across the Ile Saint-Louis would be preferable to staying in that dingy room a moment longer.

'I understand I am meant to collect a letter of some sort. If that is the case, please give it to me and I will be on my way.'

He snorted, as though I had just said the most imbecilic thing in the world, then reached under the mattress of his bed. As he did so, I noticed a pistol jutting out from under the dirty grey pillow.

'There you are,' he said. 'Take it and go. Deliver it to Mr Wilkinson as swiftly as possible. Do not stop, do not let it out of your possession for a second.'

He handed it over, and I looked at it. 'But it's not for him,' I protested. 'It is addressed to a Mr Robbins. I know of no such man.'

He stared at the ceiling, as though invoking the Lord to come and smite him.

'Yes,' he said heavily. 'How curious. However, fortunately your job is not to think but to move those little legs of yours in the right direction until you have accomplished your task. If I say it is to be handed to Mr Wilkinson, then to Mr Wilkinson it must go. Understand? Now go away.'