So, something weird happened to me yesterday.

It was lunch hour at my school, so I took a walk along the Thames. It was an overcast day, and the bridges and alleyways along the bank were practically deserted. I knew the route by heart – over the red footbridge, past the flats, under the railway bridge, through the alley with the flower sellers, and then back again – except this time, the alley with the flower sellers didn’t appear. I walked under the railway bridge as usual, avoiding the deep puddles from yesterday’s rain. The railway bridge was its usual rusted, deserted self, but there was no alleyway with flower sellers on the other side. Instead, there was a low tunnel - only an inch or so taller than I was, made of old bricks covered in lichen. And I walked in.

Inside the tunnel was humid and strangely warm, and it got warmer and more humid, like I was walking further into the belly of the earth. There were strip lights, lamps, candles, lanterns, placed at irregular intervals, so for a few paces I might have been in a glowing Aladdin’s cave, and then for a half mile or so I’d be in near darkness. And as I walked, I noticed that my watch stopped, or slowed, as though, when I was in the dark, time stopped paying attention to me. It was only the growing pain from the uneven ground and my heavy bag that told me how long I’d been gone. But I kept walking, because with every step, the thoughts of work and home that should have dragged me back, faded.

Tree roots grew through the cracks in the bricks at intervals – at times whole trees seemed to have forced their way underground, and some grew up from below, their roots threatening to trip me, and at time, branches grew sideways across the passage, so I had to climb or crawl past them. Lighted lanterns hung from the living branches, and the dead branches had lanterns too, but the candles in them were burned out.

I wondered idly if I’d ever go home. The passage got darker, and I got drowsier, but the drowsiness only made me walk on, because it didn’t occur to me to turn back. I felt my eyelids droop, and I abandoned my bag – I wouldn’t need it anymore. And I carried on walking, on, on, through the tunnel, so it was a surprise when I emerged from the darkness into a circular, lamp-lit room, with five doors.

I looked dazedly from one door to the next. The doors were crudely carved wood, and they each had a symbol scratched into them – a gargoyle, a scarecrow, a statue on a plinth, a wooden doll, and a human eye. For a moment, I was flummoxed, but then I stopped thinking, and it all seemed so simple: I’d just split myself into five! Then I could keep walking. Relieved that I’d found a solution, I cleared my mind and felt myself split into pieces, like blobs of oil in water. Then I went through the five doors.

Through the gargoyle door was a warm passageway. I yawned, and walked absentmindedly towards a moving shadow thrown by a lamp in the distance. My feet hurt, but I felt like I was floating. It was colder behind the scarecrow door, and I didn’t dare look up to see what was ahead. I stumbled onwards, and the part of me in the gargoyle passage wished I’d never walked through the scarecrow door.

I reached the lamp in the gargoyle passage. Next to it was a strange creature, lying on the damp cobbled ground. It had translucent skin like a lychee, and its pink veins and tiny, dancing heart showed through. It was wriggling away from the lamp, avoiding the light. I wrapped it in my coat and took it with me.

Through the wooden doll door, I was having no such luck. The passage curved upwards so steeply that I had to cling to the tree roots to climb, and the floor was slippery and there was no light at the end of the tunnel, so I didn’t know how far I’d have to go. I sighed and thought of myself in the gargoyle tunnel, carrying the light-hating creature.

The passage behind the statue door was short – after a few minutes of dreary walking, a mesh of tree roots blocked my path, and I leaned against them and rested and peered through the roots, down the passage. The light made the mist in the tunnel glow like stardust, and I just stayed there, and looked at it. And I carried on down the gargoyle tunnel with my bundle, and I crawled up the wooden doll tunnel, but the roots got thinner and more slippery, and the path got steeper.

Behind the door with the human eye, I emerged back into the cold, fresh air. There was the alleyway with the flower sellers where I should have been earlier, and there was the railway bridge overhead. I walked dazedly through the streets, my eyes adjusting to the colours and sunlight, my mind still in the tunnels. Behind the scarecrow door, I was caught in twisted tree roots, and I had to get free before it was too late, and I twisted and panicked and looked around for monsters. I stood in the fresh air under the railway bridge and wanted to escape from the claws of the tree roots, and I walked onwards through the gargoyle passage, carrying the creature under my coat.

Behind the statue door, I lay down to rest in the nest of tree roots, watching the glow in the mist in the distance. I didn’t want to go forward or back. I’d just stay there. Standing under the bridge by the Thames, I willed myself to escape. I could go back through the door and forget about the light and find myself back at the entrance of the tunnel. But, in my nest of tree roots, I didn’t move. At least behind the statue door I was safe. Behind the wooden doll door, I kept on crawling upwards, and I was sure I’d climbed over that thorny branch, and past that crooked brick, before, but I couldn’t be climbing in circles, could I? And in the scarecrow passage, I got more entangled in tree roots with every movement. I wished I’d never walked through that door.

Up in the street, I wanted to escape from the scarecrow corridor, and the wooden doll passage, and drag myself out from behind the statue door. I knew I’d never leave the passage behind the gargoyle door. I just kept on walking, shielding the fragile creature from the light with my coat. In the wooden doll tunnel, I stopped for a rest, clinging to the roots, but then I glared around, and kept going, because I felt sure I was almost there, wherever that was. In the scarecrow passage, I cursed my other parts for leaving me in the dark. I breathed the fresh air in the street. I could have walked back, and tried to find the entrance to the tunnel under the bridge, but I felt sure, if I went inside again, I’d lose even more of myself to the labyrinth of passageways. So the part of me that had gone through the human eye door walked back into the world. My watch said my lunch hour had almost ended, so I ignored, as best I could, the curses and screams from behind the scarecrow door, and the groans from the wooden doll passageway, and I forgot about the other parts of me, and went back to school.