Found some stairs.

I bought a bagful of battery lanterns. Small plastic camping ones, with big batteries in the bases. According to the packaging they should stay lit for several hours. I put fresh batteries in all of them before leaving.

I took the second camera, a headlamp and another flashlight strapped against my chest. Spare tapes in my jacket. The idea was to leave a lantern roughly every thirty feet so I'd have a line of lights to follow home.

It was awkward carrying everything. I walked slowly, stopping to put lights down and film a little before moving on. The corridor kept going straight. No doors, no openings. Sometimes I stopped and pointed the camera ahead for a while, though there was hardly anything for it to pick up.

By the time I'd been in there nearly two hours, I couldn't see the basement entrance at all. Just the lanterns behind me, getting smaller until I couldn't distinguish them.

Then the floor ended at a staircase.

I nearly turned back. I stood at the top for several minutes, shining both lights down. The stairs were steep enough that I couldn't see very far, and the walls continued down on either side.

But I'd spent two hours getting there. I'd carried all those lamps in and laid them out. Going home without finding out where the stairs went seemed stupid at the time. I changed the camera tape, left a lantern on the landing and started down.

For the first stretch I could have put a hand against either wall. Then I reached out and there was nothing beside me.

I stopped immediately. Turned my head to the left, then the right. The walls had ended. I could still see the steps under my feet, but beyond their edges there was only darkness. I crouched down and tried shining the chest light over the side. It didn't reach anything.

I stayed in the middle after that. Took each step slowly, looking down most of the time. I wasn't doing much filming anymore.

It took about another hour to reach the bottom.

The stairs opened onto a flat floor. I swept the light around and couldn't find a wall in any direction. It seemed to be an enormous empty room, though I couldn't see a ceiling either. I went a few paces away from the stairs, then came straight back so I wouldn't lose them.

That's when I looked at my watch properly. Three hours since I'd left the basement. I still had to climb all those stairs and walk the corridor again.

The first lanterns had already been running for three hours. So had the lights I was wearing. I'd been thinking about how long they would last going in and somehow hadn't allowed for the whole journey back.

I started climbing.

I made it home. Some of the lanterns near the basement were much dimmer by then. I left them where they were and came upstairs with the camera.

I'll need more batteries before I go back. And a watch alarm that tells me when to turn around.