Remy worked in a supermarket. A bloody supermarket. Four good Highers had qualified him to round up trolleys that lazy sods couldn’t be bothered putting back in the right place. Hefting a couple of dozen of them back to the front of the store a thousand times a day was like putting your soul in a car crusher. He knew all about living life the boring way. No reason for him to spend his free time living it like that too.

The stream turned from neon-dappled brown to murky and dark in an instant. No going back. Just on. To wherever the hell it was.

The beginning of the road to this unknown hell was Duke Street, near to the old Great Eastern Hotel. Or rather, underneath it all. He loved the fact that somewhere above his head people were tumbling in and out of pubs, going into bookies and shops, walking to ordinary places, and they had no idea that he was doing his thing beneath their feet. That was the kick.

His old man had told him all about the Molendinar, how the burn was here before Glasgow was. St Mungo came to the dear green place, a wood beside the burn, and founded the settlement that grew to become the second city of the empire. His dad knew all that stuff. He was a welder but history was his thing. That and his son were about the only thing he loved more than his twenty-pack of Embassy Regal. And it wasn’t the history that had nearly killed him.

He’d told Remy how the Molendinar used to mark the eastern boundary of the city and how it provided the water that powered the mills that industrialized the revolution. It split the cathedral from the Necropolis, separating life from death, and had the Bridge of Sighs built above it so that corpses could be carted into the cemetery. Glasgow grew on the back of the burn but it grew so much that it didn’t have room for it any more. In the 1870s, they covered it with a culvert and hid the Molendinar from view. Now it still flowed but under Duke Street, along the length of Wishart Street next to the cathedral, under Glasgow.

Hardly anyone knew it was there and fewer still knew that there was a way in. That was what made it fun. And what made it scary.

He was enjoying this. The rush, the edge, the adventure. He’d thought of doing it for ages, after he’d heard about the one guy that was known to have done it before him. Another guy like him. Another guy who did this.

The tunnel took a sharp turn to the right, a fine curve of stone wall facing him as he ducked under the arch. Rectangular slabs of old stone, two feet by one, perfectly laid. His nose was filling up with the smell, stale and musky. It was the pungent, beautiful smell of decay.

You maybe wouldn’t think that was something you would like, right? Takes all sorts. It’s nothing weird. It just smelled of the history of the city. His city. His old man’s city. You could smell every year of it.

The arch of the ceiling was less than a foot above his head but he enjoyed the luxury of that while he could. He knew it would get a lot lower. Maybe so low that he wouldn’t be able to get through. Time would tell. The stone slabs gave way to brick showing orange and white and grey in the beam of the torchlight. The burn flowed over his ankles, cold as the grave.

The first time he’d done an explore, he’d climbed high rather than hit a tunnel and it had scared him enough that he’d nearly crapped himself. He’d started off full of courage that was poured from a tap in the Hielan Jessie but that beer buzz evaporated in an instant when he realized just how high the roof of the cathedral was. High enough to die from, that’s how high. For five long minutes, he’d clung on to the one spot, petrified. It wasn’t until he was back on the ground and in one piece that he breathed and told himself he’d enjoyed it.

But all the next day, he was buzzing in a way that no amount of beer had ever done for him. He’d actually done that. And it felt fucking good. From then on he was hooked.

This explore was everything Remy had wanted it to be. The buzz ran through him like he’d known it would. Like a charge. Like drugs. Like something you couldn’t resist even if you wanted to.

The brick lining changed to concrete, low stuff that had him bent double and his pulse throbbing. It was a good fear though, he told himself. Sensible. He went on because it was what he did. No going back after that first step.

Jesus Christ. Steel piping. He never expected that. A glistening silver tunnel that spiralled in front of him, the water golden at his feet. It was almost mirrored as the steel walls threw corrugated images from one to the other. Man, this was a mindbender. It was like he was tripping and maybe, in his own way, he was.

He had three rules when he did his stuff. The same three everyone who did this had. Be safe. Don’t break in. Take nothing away with you. The least important of those was being safe. That was the one he only paid nodding observance to.

The other two were sacrosanct. Never break in anywhere. For a start, it means criminal damage and that means jail time. And it’s cheating. Use your brain instead. Don’t take anything because the idea is to uncover, to celebrate these old places as they were. Leave them that way.

The steel piping came to an end like all good things do but it was replaced by a beautiful burrowing tunnel of red brick that let him stand upright again. Maybe the worst of it was over and he’d be able to walk upright the rest of the way. Anyway, he enjoyed it while he could, a long stretch of walkway, a long stretch of the leg and the back.

When it changed, he wasn’t sure whether to celebrate or not. He was forced to duck again, not just because of the reduced height but also the stalactites that appeared like daggers from the ceiling. He bent low beneath them, on and on until the forest became a field, so many spears that the brick disappeared and he’d have sworn he was in a cave. He wasn’t back a hundred and fifty years; it was more like a thousand, ten thousand.

He was at half-height now and getting lower still. The walls grew around him, thick with solidified deposits that crowded in and suffocated. No going back. It was a stupid rule but it was his.

The ceiling was no more than two feet high now and his back was at breaking point. If he still had an adrenalin rush, he couldn’t hear it above his breathing or the pounding in his chest. It was hard work and it might be going nowhere. Nowhere that he could get through.

He was firing his torch straight ahead in the desperate hope of seeing more than the miserable amount of space he was being forced to crawl through. Wait. What was that? Darkness blocking the way forward. His heart sank at the prospect of it being the end of the journey. Another bit of him was secretly glad. Enough was enough on this jaunt.

He inched closer and saw that it wasn’t the tunnel closing up but a shape much the same size as him. Holy shit. His heart nearly stopped. It was someone else. He could make out a backpack, like the one he always took with him. Some other mad bastard was doing the same thing.

‘Hey! Are you stuck down there?’

No answer.

‘You hear me? Can you not get through? Maybe we’d better both back up.’

He waited for the reply that didn’t come. No way the guy couldn’t hear him. Shit. He crept closer, the walls tightening around him, barely able to squeeze any further. Maybe the guy was stuck.

When he got near enough, he reached out for the man. His arm extending cautiously, despite a voice inside him screaming the truth. In one moment he could see that the man had enough room not to be stuck. He saw this just as the smell hit him and he put his hand on the guy’s shoulder and tugged.

When the entire arm came away in his hand, he screamed so loud that it must have been heard all the way to Duke Street and back again.