The train doesn't stop in Innisfil. And it never will, if certain complications can't be quietly resolved. This I learn from an anonymous contractor for a private environmental assessment company hired by the county to survey the site of our future station. I shift the phone from one ear to the other and frown. "Complications?"

He lists a series of GPS coordinates. Before I've even finished jotting them down he's hung up. The line clicks and I hear a dial tone, but because I'm an idiot I say "Hello? Hello?" a few times just to make sure.

The coordinates are just outside Lefroy, so I figure I might as well drive over and have a look. I pull off at the side of the road where I see fluorescent orange ribbons tied on branches marking a footpath. The path is stomped flat, cigarette butts mashed into the mud. I follow it.

It's Sunday morning. The woods are quiet apart from the frogs and bugs and birds. I cross the railway, swatting things away from my face. In a small clearing on the far side of the tracks I find a broken surveying tripod and some torn tarp in a bed of overlapping ATV tracks. My GPS beeps: I'm only meters away from the target my nameless source has suggested, but the device is too insensitive to guide me further. I look down and follow boot prints.

That's when I come to the cave.

The entrance is a tight, twisted mouth in a jumbled outcropping of spotted limestone. I don't have a flashlight but the day is bright so I figure I'll be able to see enough to investigate a short way. I suck in my gut and carefully worm through, sliding down over a pile of rain-smoothed stones with crusty lichens on their sun-exposed faces. Once inside I blink at the gloom, eyes slowly adjusting.

Carefully I advance, splashing through shallow puddles coloured by minerals and algae -- pink or cyan or bone-white. Moisture drips patiently from the shadowed recesses on either side. I can just barely make out a fluorescent orange arrow spray-painted on the cave wall, indicating a passage. I have to get down on my hands and knees to squeeze through it.

When I rise I gasp. I've emerged into a surprisingly large cavern, lit only by a few stray shafts of sunlight spilling in from fissures overhead. But it isn't the scale, exactly, that takes my breath away: it's the fact that I'm standing in a train station.

The chamber is divided by a set of rusted rails set into half-disintegrated ties with black iron spikes. On the near side is a smooth floor of rock and a dust-covered antique bench. On the far wall are carved letters, the neat Roman serifs softened by erosion: LIFSINNI STATION.

A voice says, "Welcome to the Undertown."

I jump and shriek like a little girl.

Later, when I have finished hyperventilating into a paper bag, we meet properly. Rutger is an amateur spelunking and geohistory enthusiast from Stroud. He gets Footprints in the mail but never reads my column. I'm disappointed. "I report on local oddities," I explain.

Rutger adjusts his mining helmet and smirks. "Well Mr. Brown, you've stumbled on a doozy."

I squint into the darkness. "What is this place?"

"It's part of the underground railroad," claims Rutger.

I furrow my brow. "My history teacher taught me the name was a metaphor," I tell him. "The underground railroad was a network of people and places friendly to the cause of abolishing American slavery, and delivering those slaves to freedom in Canada. There was no actual train."

Rutger snorts. "History teacher, eh? Forget about that. This isn't on the curriculum. But it's real, son. Real as it comes. My own great-great grandfather came this way from Alabama, riding a Minoan steam locomotive brought over from the Old World when the Illuminati turned Abolitionist."

"Respectfully sir, I don't even know where to start with what's wrong with that. First of all, steam locomotives were invented in Scotland in the eighteenth century -- not three thousand years ago in Ancient Greece."

Rutger just shakes his head. "Come on," he says, turning and hopping down to the tracks. When the bobbing light from his headlamp disappears into a tunnel I slip down and jog after him, nearly tripping at a Wye Switch. I look up to see Rutger pointing his light into a wide alcove at the end of the left fork. His headlamp reveals a corroded pile of debris in the corner. I step closer, eyes widening as I'm able to make out the shape: it's a train car, perhaps three-quarters the width of a modern one, its bronze-alloy wheels misshapen and its wooden cabin collapsed. Along the sides is a green beaten-copper plaque with inlaid letters -- Hellenistic and unspeakably old. "It's from the old Talos Line," says Rutger. "They ferried Athenian nobles to safety near the end of the Peloponnesian War, right under the noses of the Spartans."

"How did they run?"

"Coal," grunts Rutger, walking back toward the station platform. "From Larium. Theophrastus designed the first engine, Diades put it to work. But it was Rome's Augustus who really grew the network, digging connections all over the Empire, setting up undertowns like this one beneath Paris, beneath London. Refuges for the enlightened from the slop and slash of history: a shadow world under our feet."

I pause and tilt my head. "Wait a minute -- beneath Athens, Paris, and...Innisfil?"

Rutger smiles sadly. "You don't understand the scope of the project, Mr. Brown. When Samuel de Champlain came to Upper Canada in 1615 the tunnels were already here. The Hurons told him stories about the great cog-and-gear boring machines that rumbled underground in the time of their ancestors, and the strange pale men who drove them -- soldiers of Louis VIII, if my theory's right -- following the secret grottoes of Kublai Khan to Alaska."

"There aren't any Mongols in Alaska!"

Rutger rolls his eyes. "Listen, Brown: there are powerful people who make sure this stuff never makes the papers. I won't go into particulars but they've got their leverage on me -- I can't speak up. You can choose not to believe, but I'm telling you straight: nobody's going to be allowed to break ground for construction around here, and if you put that in your magazine you'll never sleep soundly again."

I scoff. "So you're not only claiming that there's a secret three-thousand-year-old railway system under the cities of the world, but also that it's a going concern?"

"Naw," he says quickly, "not really. Not for years. The network's been dead ever since the elite got their hands on private jets and super-yachts. All that's left are remnants like this one. There was a time when Indian braves and freed slaves lived down here side by side in peace, but it's a vanished age. Lifsinni's a ghost town now, a waystation to nowhere."

I clamber back up onto the platform, and when I turn around to offer Rutger a hand he's gone. I peer up and down the ruined tracks but see no one, and hear no sound beyond my own breathing and the steady drip of water. "Hello? Hello?" My voice echoes back to me.

And then, ever so faintly, there is another sound: the sad howl of a steam whistle, shifting in frequency as it moves, somewhere deep and far away.

I bolt like a rabbit, skinning my hands as I squeeze through the entrance. I stumble out into the woods and run back to my car, pausing to catch my breath only when my shaking hands can't get the key into the lock. When I do manage to get in I just sit there for a while, hands on the wheel, staring at nothing and feeling weird.

I promise myself I'll come back tomorrow, but you and I both know I'll never find the entrance again. I'll find a giant boulder, or a pile of broken rocks. Maybe a featureless concrete slab. But no cave. No Undertown. And it figures, right?

Because I made this story up. There really is no Undertown. Honestly, there's no such place. Just put it out of your head.

IF YOU HAVE ENJOYED READING THIS STORY, PLEASE CONSIDER LEAVING A SMALL TIP. A PAYPAL ACCOUNT IS NOT REQUIRED. THANK YOU VERY MUCH. YOURS TRULY, C. BROWN.