I first saw the strange young man whilst sipping a beaker of my favourite ale (the cheapest), sitting in a corner of the Green Lattis. Mind you, there was nothing unusual about seeing a stranger in Bristol at the beginning of August: it was the time of Saint James's fair.

The priory had originally been granted a nine-day charter for this annual event, but over the years its time had gradually lengthened, first to a fortnight, then to three weeks until, in this year of Our Lord, 1480, it seemed to the inhabitants' blunted senses to have been prolonged indefinitely. Although it was held outside the city walls, drunken brawls and dusk-to-dawn revelry meant sleepless nights for those of us who dwelt within earshot of the priory; and the house in Small Street, where I lived with my wife and three children, reverberated constantly to the shouts and cries of the hundreds of traders who converged on Bristol from all over the kingdom. It was the boast of the prior that Saint James's fair had become one of the most popular in the land.

By day, the city, and particularly Bristol's many alehouses and taverns, echoed with the strange and – to our west country ears – uncouth accents of certain parts of England that were as foreign to us as those of France or Brittany or the Low Countries. In fact, we had greater difficulty understanding our fellow countrymen from the unknown north and the borders of Scotland than we did the sailors from across the Narrow Sea, who disembarked from the ships that tied up daily along the Bristol backs and wharves.

So, as I said, seeing a stranger that sunny August morning in the Green Lattis was no more surprising than observing an ant on an anthill, and I probably wouldn't have spared him a second glance, had I not been seized by the sudden conviction that I recognized him. Well, perhaps not that, but his face was somehow familiar to me. I had either met him before somewhere, or he reminded me of someone I knew or had once known. Not that his looks were in any way remarkable. It was a small face under a thatch of dark hair, with a pair of equally dark, very bright blue eyes set a little too far apart, a sharp, inquisitive nose and a wide, thin mouth that seemed to be constantly on the verge of smiling. He was not old; certainly younger than myself, and I therefore judged him to be in his early twenties. (At this time, I was approaching my twenty-eighth birthday.) There was something of the Celt in his appearance. A Welshman, I thought, until he spoke. Then I could hear the soft, lilting cadences of southern Ireland.

After that, I lost interest. The only Irishmen with whom I was acquainted wouldn't show themselves openly in a respectable inn like the Lattis, but be tucked away in Marsh Street – Little Ireland as it was known – carrying on their nefarious and totally illegal trade of slaving. (Officially, selling your unwanted relatives into captivity in Ireland had been unknown in Bristol for several centuries. Unofficially, it lined a lot of people's pockets, including those of the great and the good. Especially those of the great and the good.) Needless to say, and as all readers of my previous chronicles will know without being told, my past and infrequent dealings with these gentlemen had been purely in the line of duty, whilst pursuing one of my investigations.

At present, after a short but successful visit to London in the late spring to solve a murder for my friend and patron, Richard, Duke of Gloucester, I had reverted to my proper trade of chapman, much to the relief of Adela, my longsuffering wife. With three voracious mouths besides our own to feed, and a dog who considered it beneath his dignity to provide himself with sustenance from amongst the vermin infesting the city streets, a steady supply of money was essential. High summer, of course, was the time to be striding along the open roads, free of family responsibilities; to be walking narrow, crooked paths or wide rutted highways; to be spending moon-washed nights sleeping in little, sweet-smelling copses, shaggy with leaves. Instead, my attempts at sleep were being rendered hideous by heat, noise and, as often as not, the nocturnal tantrums of my two-year-old son, Adam. But after being absent earlier in the year, I felt in duty bound to ply my trade nearer to home, in the villages and hamlets around the city.

Today, however, I had been restocking my depleted pack from the local market and from the ships at anchor along the banks of the rivers Frome and Avon. I had returned home for my dinner at ten o'clock, but been driven out again, not so much by Adela – who was always willing to allow me a short rest after meals – but by the antics of Nicholas and Elizabeth, my five-year-old stepson and my first-marriage daughter. Closer than two peas in a pod, and with the same predilection for rowdy games, they had, today, been running up and downstairs screaming and shouting at the tops of their voices. (And if you are wondering how a poor chapman came to be living in a two-storeyed house in Small Street, I refer you again to my previous works.)

I was feeling so fraught on leaving the house that a draught of ale in a quiet corner of the Green Lattis had become not merely desirable, but essential if I were to do any work for the remainder of the day. And it was while I was downing the contents of my second beaker that I spotted the stranger.

There were a lot of people in the Lattis that morning, and this stranger seemed intent on speaking to as many of them as possible, wandering from bench to bench and obviously asking some question; a question to which he was getting no satisfactory answer, judging by the number of shaking heads, pursed lips and expressions of regret on people's faces. It was as he approached my corner that I heard the Irish lilt in his voice, yet at the same time, oddly, I thought I also recognized an underlying west country burr. This, together with the growing conviction that I had met him somewhere before, a long time ago, made me follow his progress around the taproom with the greatest interest.

As though suddenly conscious of my eyes boring into his back, he swung abruptly in my direction and returned my stare with an intensity I found unnerving. Hurriedly, I looked away, swallowing the rest of my ale and, at the same time, fumbling with the pack at my feet, preparatory to leaving. My dog, Hercules, a small mongrel with big ideas, whom Adela had insisted I bring with me, sat up and barked.

'He's a nice little dog,' the stranger remarked, sitting down on the bench beside me, where there just happened to be an empty space.

'He thinks so.'

The Irishman laughed, showing a mouthful of extremely good teeth. Then he hesitated, as though uncertain how to continue, a reticence I hadn't noticed in his dealings with the other customers.

'You're making some enquiries,' I prompted. 'At least, that's my impression.'

The young man nodded. 'That's right. My brother – my younger brother – joined the crew of Master Jay's carvel when it anchored in Waterford harbour about three weeks ago. I was hoping to glean some news of its return, or at least to hear that it had been sighted somewhere by one of the ships putting in to port today. But it seems there's been no word. You wouldn't happen to know anything, I suppose?'

'No, I'm afraid not.' My companion looked crestfallen and I tried to cheer him. 'Three weeks isn't so long, is it? Not when you're searching for...