The map showed me the way through the places where people put the things they had forgotten. There were a number of entry points: through coal holes into cellars, into the pages of photo albums sold on stalls in the back streets of Brick Lane. I entered in a derelict house in a row due to be demolished. I packed a torch and some sandwiches and climbed the stairs, hoisted myself up from a banister into the attic.

The trail on the map led me through anonymous places, making my way through secret portals, activated by a loose brick or a wobbly rafter. There were attics of people I would never know, boxes of clothes tracing a life from baby-grows to teenage gaudy. Always shoeboxes of old photographs and postcards with faded ink. It was all so tempting to linger, to pass all these trinkets of domestic unconscious through my fingers, but the map led me on.

One cramped space, some portioned-off loft above a single bedroom, had been used to store only one item: spread out like the diaphanous wings of an insect, my torch picked out the filigree of a wedding dress; worn for one day and then left here forever.

Down chimneys to cellars of rusting gardening equipment. Up again to other attics with boxes of books, toys. One with an impressive collection of vintage pornography.

Sometimes, now I was in inhabited regions, I would hear voices, people moving around.

I consulted the map. I had been moving through the city but my goal was still some way off. I carried on. I heard a couple arguing although I could not make out the words; around me in the attic were the remnants of the life they'd once lived, travel books to exotic places, backpacks sewn with patches from Malaysia, Australia. Everything had begun to rot. I wanted to open the trapdoor and call down, tell them that all they had to do was come up and retrieve their past. But I had other priorities.

All the years that had passed since I had first left my destination had been a series of false starts. That job as a salesman that had ended with a court case. The disastrous period as a barman in Menorca when I'd chased after women too young for me and drunk my wages. But the map would solve all that.

At last I began to recognise things. An old neighbour's obsessively folded and bagged children's clothes. The train magazines and Hornby railway of my friend from a few houses down. Then I found the familiar trappings of my childhood: the cardboard box of Airfix planes and plastic soldiers, my Mamod steam engine. From below were voices I recognised even in murmur. The words were not important. Lifting the door from the hatch, I looked down onto the upstairs landing. I switched off my torch, folded away the map, and climbed out; hung for a moment by my hands and then dropped into my past.