St Paul’s Labyrinth. Jeroen Windmeijer

and shrill, like a frightened child’s. All the bravura he’d put on display earlier was gone in an instant. He bent down to pick up his helmet.

      Peter looked behind him at the spot where the faint light from outside permeated the thick, black darkness. They heard Daniël shout something, but couldn’t make out the words. It was only then that Peter noticed that Arnold was bleeding from a large scratch on his forehead.

      ‘You’re bleeding, Arnold. We should go back.’

      ‘It’s nothing,’ Arnold said, wiping the blood from his brow with his sleeve. ‘I feel fine. Don’t worry.’

      Peter walked back to the spot where they had entered the tunnel and shouted up to the surface. ‘Did you say something, Daniël?’

      ‘We’ve thrown a rope down!’ Janna shouted back. ‘Can you see it?’

      Peter looked down and saw a long rope coiled near his feet.

      ‘Like Ariadne, remember, in Knossos. In the Minotaur’s labyrinth.’

      ‘Thanks! But we’re coming back up in a minute!’ he shouted. His words were meant for Arnold rather than Janna, but Arnold had already moved a few paces further down from the torch.

      Peter put the end of the rope under a pile of bricks that had been left when the tunnel collapsed. If they didn’t pull on it too hard, it would stay where it was. He had no intention of going any further into the tunnel than the rope was long.

      ‘I hope your initial curiosity has been satisfied,’ he said as he unwound the thin, strong rope. ‘Let’s go a bit further. We’ve got about thirty metres of rope here, I think.’

      But Arnold had already walked away. Peter couldn’t tell if this was the overconfidence of a drunkard, or the burning desire to beat him to an archaeological scoop. Peter quickened his step so that he wouldn’t fall too far behind.

      All at once, the light from Arnold’s headlamp vanished.

      ‘Arnold!’ Peter shouted. His voice echoed through the chamber.

      ‘I’m here!’ came the distant reply. Peter realised that the tunnel must have curved away from him so that the light from Arnold’s helmet was no longer visible.

      They had walked about twenty metres now; Peter had let out more than two-thirds of the rope.

      He walked further down the tunnel and saw that he had been right about the bend. Arnold came into view again, standing still and staring upwards as though there was something fascinating there. Peter stood next to him and looked at the same spot, but saw nothing.

      ‘What are you looking at?’

      ‘I’m not looking, I’m listening.’ He raised his hand and pointed a finger in the air. ‘Shush.’

      Peter listened intently. He could hear the faint gurgle of flowing water. It was coming from … below them.

      Arnold stamped his foot on the ground. ‘Ab urbe condita … ’ he said solemnly. ‘Are you familiar with the work of Livy?’

      Arnold was fond of demonstrating the knowledge of Greek and Latin he’d gained at grammar school, although in practice this was limited to recitations of a few well-known sayings and proverbs.

      From the foundation of the city … The opening lines of Livy’s history of the city of Rome.

      ‘I wouldn’t go as far as to say I was familiar with his work,’ Peter replied, ‘but I know that saying, naturally.’

      ‘Exactly, this is … It looks like this was planned when the city was founded. I believe what we hear below us is part of a drainage system. It must be … You would usually expect to see groundwater this far down. You wouldn’t be able to dig this without anyone knowing about it. Not if the city had already been built above you.’

      Peter was becoming increasingly excited about what they had found. They couldn’t even begin to imagine what the consequences of their discovery would be. But at the same time, he felt a growing disquiet. A young man covered in blood in subterranean passage … Who knew what other macabre things took place here?

      ‘Listen, Arnold, this is all fantastic, and you’re … We’re the first people to come down here, apart from the poor man who ended up under a pile of rubble this afternoon … But let’s leave it at this for now. We’ve satisfied our initial curiosity. We can come back tomorrow with more people, more light, and we definitely need more rope. It’d be irresponsible of us to go further now. We don’t know what’s down there. You’ve wounded your head … After the weekend, we’ll have the Geo—’

      But Arnold was deaf to his objections and walked away from him again. ‘Just a bit further. This is …’

      The beams from their headlamps cast grotesque shadows on the walls. Their footsteps sounded hollow.

      We must be under the Hooglandse Kerk by now, Peter thought. But there was no sign of a way out or up. When he looked around him, he had to admit that he was impressed by the neatly constructed walls, by the solid arch of the ceiling, by the dry, even floor, by the drainage system.

      They were running out of rope. It would reach as far as where Arnold was standing now, a few metres away from Peter.

      Arnold carried on walking.

      ‘Hey, will you listen to me? We’re going back. We can go further tomorrow.’ Peter stood with the end of the rope in his hand, not sure what to do next. His headlamp illuminated the path ahead and shone on Arnold’s back.

      ‘We can’t really get lost down here. We’ve not seen any side tunnels, or any stairs … This is sensational, Peter. I just want to walk a little further.’

      Aware that he was likely to lose sight of Arnold again, Peter put the rope down. He laid it carefully on the ground, next to the wall and well in sight. By the time he looked up again, his companion’s light had vanished.

      The silence and darkness seemed to have intensified, as though Arnold had literally been swallowed up.

      Peter took a few uncertain steps forward and saw that the tunnel formed a T-junction and split off to the left and right a few metres ahead of him.

      ‘Arnold?’ he said. He cupped his hands around his mouth and called out Arnold’s name again, but there was no response.

      He was suddenly aware of how cold and damp it was. What should he do now? He called out again, but all that came back was the echo of his own voice. He began to half-heartedly go down the tunnel on the right, but after a few metres, he reached a wall. This part of the tunnel was a dead end.

      He turned around, making sure that he didn’t let go of the wall. Without the rope, it was his only guide. He went back to the point where the path split and then walked a couple of metres into the other tunnel. He called Arnold’s name again and it came out like a hiss. ‘Arnold!’

      He took a few more apprehensive steps.

      ‘Arnold!’ He was screaming now. His voice died away almost instantly.

      He was jarred by the sudden, chilling sensation that he was being observed by something or someone hiding just beyond the reach of his headlamp beam. He was suddenly very scared, like a small child in the night, afraid of the monsters under his bed. He wanted to get out of here, go back up into the sunlight.

      ‘Hello,’ he said haltingly. ‘Hello? Is anyone there?’

      He had to get out of here. Now.

      But before he’d even started walking back out of the tunnel, his headlamp blinked erratically and then went out. Now he was in total darkness. An instinctive fear of the dark – a deep, primitive, irrational fear – overwhelmed him. He flailed his fists around to ward off an invisible enemy.

      ‘Yea, though I walk through the valley of the shadow of death, I will fear no evil, for thou art with me …’ he murmured to himself.

      His