‘Did you not hear the announcement to evacuate?’
I shake my head, wearing my most earnest expression. ‘No, I haven’t heard anything. Why … has something happened?’
‘Surely someone told you this part of the museum is off-limits?’ He seems entirely bemused by my presence.
I shake my head again. I need to distract him with a change of topic. Discreetly, I take in as much information as I can, my eyes flicking over his form. There’s not much to go on, because he’s in uniform, but I do find a few clues.
‘Do you like dogs?’ I say, thinking on my feet. ‘I love them!’
His eyes light up. ‘I love dogs too! I have four of my own,’ he says proudly.
‘You’re so lucky,’ I say. ‘I’d love a dog, but my dad won’t let me have one.’
His radio crackles and a female voice comes through, issuing instructions. ‘Oh, that’s for me,’ he says. ‘Just get your things and go home.’
‘OK … thanks! I hope my school teacher won’t mind too much if I’m late with my project.’
‘Can’t help you there, I’m afraid. Don’t forget your coat,’ he says, pointing to a door marked STAFF ONLY. As long as he’s watching, I can’t head back the way I came in, so I obediently go the way he indicates.
It takes me into another hallway, with another set of stairs leading down. I run down to the basement, wondering if there might be some way back to the tunnel from here. At the bottom there’s a door.
I push it open.
I step inside and quickly shut the door behind me. I’m in darkness and I fumble for a moment before finding the light switch. My nostrils fill with the smell of damp stone.
The single bulb flickers and then comes on; it sheds barely enough light to see by, and casts weird shadows around the room.
The basement itself is ordinary enough – concrete floor and ceiling, with three walls also made of concrete. The fourth wall, facing me, is made of brick and looks older. There are several sets of metal shelves against the walls, stacked with a variety of cleaning products – sponges and mops, buckets and basins, bottles of bleach and disinfectant. There’s only one other object in the room, over in the far corner.
It’s as big as a bear, and so blackened with age it takes me a minute to work out what it is – a boiler, old and long retired. It was probably left here because it was too much trouble to dismantle it and lug it up the narrow stairs. The squatting lump of metal is knuckled with rivets and valves. There are several water pipes leading up from it, but these have been chopped off, and now stop short of the ceiling.
I sniff the air. Not just damp, but the scent of bleach. This could be from the army of mop buckets down here, but the smell is strong and fresh. By the light of the single, naked light bulb, I look around at the floor, then crouch to run my finger over it. Dust – lots of it.
Over in the corner, by the old boiler, the floor is darker. I walk over. Yes – the concrete here has been scrubbed recently and is still damp. Why would someone clean this patch but not the rest of the room?
In my mind’s eye, I conjure up a Polaroid camera. It appears in front of me, hovering in the air. I hold the imaginary camera steady, and start to take some snaps of the room. Each photo scrolls lazily out of a slot on the camera and develops from black to a colour image. When I’ve taken enough pictures, I file them away in my memory.
Now for my next job. I fish out the plastic vial and use the cotton bud to swab the floor. I could be wrong, but I have a funny feeling about this wet patch. So I place the swab safely back inside the vial for analysis in Brianna’s secret lab.
Then I step up to the disused boiler. It’s covered in dust and clearly hasn’t been used in a very long time. The pipes are cut off, so it can’t have leaked. Why would anyone need to clean up here?
Peering into the darkness behind the boiler, I can’t make anything out. On my keyring I have a tiny torch, which my dad gave me last Christmas as a stocking filler, so I point it into the darkness. There isn’t much there, although … I peer more closely. Yes! It looks like there could be a hole in the wall! I can’t see into it from this angle, but the back of the boiler is completely free from dust. It seems as though someone’s been crawling around in this area.
There’s only one thing for it. Clamping the torch between my teeth, I shuffle forward and crouch down until I’m fully enclosed inside the cramped space. I can see it now, just as I suspected – a hole in the brick wall, big enough for a grown human being to fit through. Looking down at the dirty floor, I can just make out a boot print. Someone has definitely been through here recently!
Steeling myself, I start to crawl forward. My keyring torch doesn’t do much to illuminate the space, but by moving the beam around I can see tunnel walls opening up. I wish I hadn’t left my powerful head torch in the cavern under the Serpentine.
As I go through the underground passage, the brick surface changes, first to something like concrete, then to a material resembling bedrock, chipped away roughly with a chisel or a small pickaxe. There are no signs of activity here, and it’s completely silent. I continue, slightly crouched, but hurrying along.
After about thirty metres, the corridor begins to slope down and, a little further on, the space starts to open out once again. Here, the walls are lined with brick, as the rough-hewn tunnel gives way to a carefully built structure, like a Victorian sewer. Thankfully, this is much cleaner and drier, though!
I carry on, now able to stand up fully, holding the torch in front of me like a miniature shield. Its beam isn’t strong enough to fully light the way, and the area ahead looks especially dark and unwelcoming. Until this moment, I’ve been caught up in the chase. Now, though, I’m suddenly aware of my own smallness. What, or who, might I find down here?
I hesitate. I think of Dad, and my cosy room under the eaves of the cottage.
Then Hercule Poirot speaks to me in the darkness: ‘Ma chère Agathe, you have stumbled upon un petit mystère, non? You are not going to turn back now?’
Too right I’m not. I push on.
Twenty more steps and the space opens out into an even wider passage. Here, my tiny light seems brighter than it did in the brick section, because the walls around me are lined with white ceramic tiles which despite being grimy still manage to reflect a little of the beam back towards me. The pale expanse is broken up by bands of tiles in a dark colour, burgundy perhaps, or purple – it’s hard to tell in this light under the layers of dirt. But there’s something very familiar about them. It takes me a while to realise what it is, out of context as they are.
Of course! These are the tiles used across London to line the walls of Tube stations! In the days when many Londoners couldn’t read, the patterns were used to signal the different stations.
Over the last few years, I’ve travelled through almost all the stations on the Tube map, except for some of the ones further out. I’ve taken mental pictures of all the tile designs, and I call them to mind now. The pictures appear in front of me as Polaroids, stuck with brass pins to a corkboard that’s hanging on the wall.
I check through all of them quickly, but can’t identify the particular arrangement of tiles I’m seeing now – the two burgundy bands separated by a band of white. I turn away from the images.
This is a conundrum – a Tube station which is not a Tube station, right