I first had the dream the night after we moved into our new house.

     In the dream, I was walking along the corridor of an old house, the kind of large mansion that the minor nobility used to inhabit back in the eighteenth and nineteenth centuries. The walls were panelled with dark, varnished wood with paintings hung on them. Landscapes for the most part, although I paused before one which held the age-darkened image of a fierce looking man. He was dressed expensively, and he was wearing a ring on his left hand in which a large, solitary jewel gleamed in the light of the silvery moon. In the strange way of dreams, it seemed as though I knew this man, although my waking self had no idea who he was or why I should feel a connection with him.

     The corridor connected two wings of the mansion and there were windows in the left hand wall. Through the windows I could see the same low hills that are visible from the windows of my new house, but the electricity pylons that form a line along them were absent, having been replaced by huge, ancient trees. At the end of the corridor was a room, and in the room was a door. On the other side of the door was a staircase leading down into a dark, damp basement.

     Ordinarily, my dreams tend to fade quickly when I wake up, but this one stayed with me in vivid detail and it was still with me when morning came, still so sharp and clear that I could almost smell the close, stuffy air, heavy with moisture and mildew. I remembered, in the dream, thinking that I really should do something about the damp creeping up from the heavy, waterlogged ground on which the mansion sat, but that bringing workmen into the house ran the risk that they might see something they shouldn't.

     I put it out of my mind as Sophie and I rose for the first time in our new house. All our belongings were still in crates and boxes and we had too much else to think about as we set about settling in. We were happy and excited. We were still in the first glow of love, having gotten married just a few months earlier, and this was our first full day in our very own house after having been crowded in with my parents for so long. Only rented, it was true, but ours none the less, and the council sometimes left their tenants buy their houses. We happily speculated that it might be our house for real one day. The ground around it was large enough for a couple more bedrooms if we decided to have children one day, and we might even grow old and die there, in the fullness of time. The house had a good feel to it. We could both easily imagine spending the rest of our lives in it.

     The next night, though, I had the dream again. Exactly the same in every detail, except that this time I reached the bottom of the staircase to find a sturdy wooden door locked by a huge brass key that I could feel in the pocket of my waistcoat. When I mentioned it to Sophie, though, she didn’t think anything of it. You just think it was the same dream, she'd said as she sat up in bed and pushed her sleep-tangled hair out of her eyes. The sight of her, bare from the waist up as the bedsheets fell to her waist, distracted me enough that I didn't argue with her, even though I knew that it had, indeed, been the same dream, every detail sharp and clear.

      Later that day, though, as I was wandering around the garden, scowling at the newly laid turf that was already drying up and curling at the edges in the summer heat, I justified it to myself by telling myself that it had been caused by some television drama I'd seen and that had struck a chord in my memory. I knew, even as I was thinking it, that it was a rubbish theory, but back then I hadn't been, in any way, a spiritual or superstitious person and I refused to contemplate that it might have had a deeper meaning. When I had the same dream a third time, though, this time getting as far as inserting the key and exerting enough force to turn the great, heavy lock, I started taking sleeping pills to keep it from returning. This time, there had been the knowledge that there was something on the other side of that door, something terrible, and I had no wish to find out what it was. The pills worked, and the dream didn't come again.

     It wasn't just our house that was new. The whole street was new. The whole estate, covering several hectares of what had been waste ground on which unscrupulous tradesmen had dumped their waste. All our neighbours were new to the area, therefore, and there was a great deal of happy and excited getting to know each other. The people in the house next to ours, George and Claire Wensleydale, invited us over for an evening meal, and we accepted with pleasure.

     George was a tall man with long fingers that felt cool and clammy as we shook hands, while Claire wore a thick, woolly jumper that must have been hot in August. She was severely short sighted and wore glasses with lenses so thick that they made her eyes appear almost comically small. They were pleasant and bubbly, though, and made us feel welcome as they invited us in. Like us, most of their belongings were still in boxes, but they'd already got their living room sorted out with a television mounted on the wall next to shelves packed full of DVD’s and a glass cabinet full of delicate looking porcelain tableware. “It belonged to by grandmother,” said Claire, bubbling with pleasure when she saw Sophie looking at it. “Royal Worcester. Too good to actually use, of course, unless the King comes to dinner one day.”

     They served us a meal of roast beef, parsnips and potatoes. It was good, but I thought Sophie could have made a better job of it. The parsnips were a bit soft for my liking and the beef a little over cooked, but we both assured them that it was delicious and ate it all, along with the apple pie and cream that followed. As we ate we told each other about ourselves. George was a schoolteacher, it turned out, while Claire had trained as a nurse, although she'd never put the training to use. She’d put her hospital career on hold when she met George, and had opted for the life of a housewife instead. “If he should ever lose his job at Porterhouse, though, it’s good to know that I can get a job to support us,” she'd said, and Sophie and I had agreed, smiling pleasantly.

     It was then our turn to tell them about ourselves. I told them that I was an apprentice antiques dealer, working for a crusty old man called Frank Tipping who ran a shop in York, fifty miles away. It was a bit of a commute, but I was hoping to open a shop of my own somewhere closer, as soon as I could afford to. George and Claire nodded their heads as if this was what they'd expected me to say, but I could see the surprise in their eyes. They'd clearly expected me to say that I was in advertising or something. I've been told that I had the look of a junior executive, someone on the management ladder. Maybe it was because of my slim, healthy build. The look of a man who takes care of himself, who keeps his weight down and his body in trim while not spending a lot of time exercising, except maybe for an hour or two in the squash court at the end of the day to compensate for a mostly sedentary working life. The truth was that, if things had been otherwise, I could easily have made a career for myself along those lines. I had the education and the intelligence, but I didn't feel that I knew them well enough to explain my life choices. To tell them that I'd always had a fascination with old things. A powerful desire to know more about the past. I know that some people are happy to bare their souls to complete strangers like that, but I just didn’t feel comfortable with the idea, and so I just gave them the bare facts and left it at that.

     Sophie was another reason for their confusion. She was spectacularly beautiful. Slim and graceful but with curves in all the right places. She looked like a trophy wife, a woman who might have married a millionaire and spent the rest of her life sunbathing on a yacht. She looked like the wife of a manager or a premier league footballer, not the wife of an antiques dealer. I saw our neighbours sharing a look of curiosity, as if wondering why she’d thrown in her lot with me when she could have done so much better. Sophie just smiled, though, and began talking about the Cezanne print hanging on the wall beside the table and saying that he was one of her very favourite artists. How we'd come to be a couple, the way something had just clicked between us the first time we'd met, at my friend Dave’s wedding, that was something else that neither of us felt like sharing with people we'd met for the first time only the day before. Maybe, if fortune had allowed us to know each other for several years, we might eventually have reached the point where we’d have told them these things, but it wasn't to be.

     When the meal was over and we were getting ready to leave, I saw another print hanging on the wall, beside the stairs up to the first floor. This one was a copy of an old map showing the local area as it had been a couple of hundred years before and I stared at it in fascination. All the towns were smaller, some of them nothing more than a cluster of buildings around a crossroads, towns that now had populations of tens of thousands. The roads running between them zigged and zagged their way around the outlines of fields, even the ones that had been major highways back then, and small, irregularly shaped patches of woodland were scattered across the map. The only almost straight line was the thick black track of the Great Northern Line, the railway that had once serviced this part of the country. It was pretty much the only thing that would have appeared unchanged on a modern map.

     I stood closer to look at the names written on the map in the archaic, barely legible typeface that had been typical of maps of this era. The words ‘Little Leighs' were written across a patch of farmland, with no way of telling whether it referred to the stream that ran past it or the patch of woodland close by. Or perhaps it just referred to that whole area in general. A tiny cluster of buildings in the middle of nowhere was labelled ‘Little Braxted’. I'd never heard of the place, and I assumed that the tiny village had been swallowed up by a larger town and the name lost to history. I had heard of Folkbourne and Willhambury. I'd seen their names on road signs while driving here from York, but the name of Gill Farm was new to me. It was, as far as I could see, the only farm mentioned by name, even though virtually the whole map was farmland. Some guy called Gill must have been a major landowner back in the day, I thought.

     I searched for the part of the map on which our new homes now stood, and George came closer to point it out to me. “There we are,” he said, pointing to a spot that contained nothing but fields. “That’s where we are. Right there.”

     I nodded silently as I examined the area. There was something there, I saw. A tiny black square with a name that I had to squint to make out. Towen Hall. “What's that?” I said, totally fixated on it.

     “An old manor house,” said George brightly. “A minor aristocrat once lived here. On this very spot! Well, on your very spot actually. We did a bit of research, incredible what you can find on the internet these days, and it turns out that your house stands almost exactly where the manor’s east wing once stood.”

     “What about the west wing?” asked Sophie.

     “At the end of your garden,” replied George. “It was surrounded by grounds and gardens of course, but your house stands where the manor itself once stood.”

     I thought about the dream I'd been having. Just a coincidence, I thought. “Towen Hall?” I said.

     “We thought at first it was an old spelling for town hall,” said Claire. “We thought there might have been a town there once and the manor house had once been its town hall or something.”

     “Except there was never a town there,” added George. “We checked.”

     “There was a Stephen King story that had a place called a Towen,” said Sophie, her forehead creased with thought. She loved those kind of horror stories. “I think he said in the story that Towen means a place of ritual sacrifice.”

     “I know the story you mean,” said George. “We checked that as well and there's no such word. Stephen King seems to have just made it up for the story. No, I’m afraid the truth is rather more prosaic. Towen was the name of the man who lived there. Charles Towen.”

     “Bit of an unpleasant character by all accounts,” said Claire, grinning brightly. “A recluse who lived alone except for a couple of servants who also kept to themselves. The house burned down in the thirties and this whole area was left wild and overgrown until they decided to build the estate here.”

     “Burned down?” said Sophie, her eyes shining with delight, and I smiled to myself. I knew she was imagining a crowd of villagers with pitchforks and burning torches storming the mansion to put an end to his ritual sacrifices.

     “An accident, by all accounts,” said George, who'd also seemed to guess her thoughts. “There was no suggestion of anything improper having happened. Charles Towen died in the fire, though, along with one of his servants, the gardener and caretaker. Only his wife, the cook, survived, along with their child.”

     I thought about the old manor house when we’d returned to our own house, and I decided to stop taking the sleeping pills. I've never liked taking any kind of medicine, even something as trivial and harmless as this, and I thought maybe the dreams would have stopped by now. And even if they hadn’t stopped, I was curious to know what happened next, when my dream self arrived at the thick, wooden door at the bottom of the staircase. After just a couple of days I'd forgotten the strange quality of the dream that had so disturbed me, the reason I’d not wanted to experience it again. It had become simply a mystery to me. I was intrigued by the possibility that there might be a connection between my dream mansion and the real mansion that had once stood on this spot. My mind tried to conjure up a rational explanation for it. Maybe, when I'd picked this house, having, for some reason, preferred it to all the other houses in the street even to the extent of offering to pay a little more rent in order to get it, maybe I'd also looked at some old maps, as George had done. Maybe I'd seen the mansion marked on the map and then forgotten all about it except for some lingering memory that had stayed in my subconscious, resurfacing at night and fuelling the strange dream.

     When the dream did come again, it was a little different in that I knew I was dreaming. I was able to take note of how long the corridor was, and when I got to the room at the end I was able to make myself go to the window and look out. There was a low but wide depression between the house and the hills that rose beyond, I saw. Filled with stubby shrubs and with a narrow, fast moving brook at the bottom. That depression, and the brook at the bottom, was still there in my day, and I was able to estimate the distance between it and the entrance to the staircase. Maybe, just maybe, the staircase was still there in the present day, the entrance buried under a few feet of thick, clay soil and tangled tree roots.

     I allowed the dream to return to its natural course and opened the door to the staircase. As I descended I counted the steps. The basement couldn’t be lower than the brook, I knew, or water would seep in and it would flood. I knew that the brook was fifty metres lower than the new house because I’d checked before signing the rental agreement. Heavy rainfall and flooding was becoming more common as climate change kicked in, and I'd wanted to make sure we weren’t flooded out by the autumn rains. Sure enough, I reached the bottom of the staircase after having descended only thirty metres or so, but all my attention to detail must have disturbed the dream because, to my annoyance, I woke up before reaching the thick, wooden door and, no matter how much I tried, I couldn’t get the dream to return that night.

     The next morning, though, I went out into the garden and tried to work out where the staircase would be if, by some strange miracle, my dream really was a memory of the past. I remembered how close to the edge of the depression I’d been when I looked out through the window and, assuming it hadn’t widened in the intervening years, I soon found the spot where I thought I'd been. My wife, seeing me wandering around on the dry, curling, newly laid turfs of grass, came out to join me and asked me what I was doing.

     There was a place, about five or six feet across, where the newly laid grass was greener and healthier looking than elsewhere and I pointed it out to her. “Look at that,” I said. “There's something different about the ground here. That means the soil’s deeper here, allowing it to hold more water.”

     She nodded as she looked at it. “Maybe someone dug a hole here once and filled it in again.” She turned to Look at me, her face shining with wicked delight. “Maybe there’s a body buried here!”

     I smiled back at her. “Actually, I was thinking about Charles Town’s mansion,” I replied. “The one George said once stood on this very spot. I was wondering whether it had a basement.”

     She stared, her delight growing greater. “His wine cellar perhaps!” she said. “Or the place where he carried out his blasphemous occult ceremonies.”

     “You know, I worry sometimes about the kind of books you like to read.”

     “You think I should stick to soppy romances, or brainless young adult rubbish about pubescent girls falling in love with vampires?”

     “Well...”

     “We'll need picks and spades. We'll have to pay a visit to the garden centre.”

     I stared at her in wonder and relief. I'd been wondering how to persuade her to let me dig it out. “If, somehow, there really is a basement under there, do we own whatever we find down there?”

     “Well, it is on our land.”

     “It's not our land. We only rent the place, remember?”

     “Well then, if we do find anything, we simply don't tell anyone. We say we found it on one of your antique hunting trips. You're always buying dusty old stuff to sell in Tipping’s. We've still got boxes of the stuff in the spare room.”

     “All of it documented and provenanced,” I replied. “Anything we find down there won't be.”

     “Let's see if there is anything down there first, and worry about it then,” replied Sophie, smiling broadly. “Even if there is a basement, there’s probably nothing in it but dust and cobwebs.”

     “More than likely,” I agreed. “When do you want to go get the picks and spades?”

     “How about right now?”