Finally, there was an opening as big as my hand. I kept going, using rocks as tools to chip away at the hole, then reached my arm in as far as my shoulder and heaved until it was wide enough for me to get through.

I took a deep breath, steeling myself, I suppose, to cope with whatever might be to come, then clambered into the prison of rock and stone.

Straight away, the smell of air long undisturbed hit me, musty and expectant after its long confinement.

After a few paces, the tunnel curved a little to the left, then immediately opened out into an extraordinary, soaring cavern, the dimensions of a cathedral. In awe at the sheer scale of it, I shone the torch at the walls and up above my head. The beam vanished into the darkness.

‘A city in the mountains,’ I muttered.

For a moment, a feeling of calm came over me, a kind of peace to be in so ancient a place. Their refuge, she’d called it. A refuge that became a tomb.

A long sigh of relief escaped from between my lips. There was nothing to see. Until that moment, I did not realise how much I’d started to fear what I might find.

Fabrissa could not be here. It had taken me long enough to break down the obstruction and it seemed unlikely there would be another way in.

‘But then where are you?’ I whispered into the silence, at last facing what common sense had told me all along. I shook my head. I’d felt so sure I would find her. And, in truth, I somehow felt her presence at my side. Somewhere close by.

I shone the torch around the cave, sending the beam darting into every crevice. Suddenly, I stopped. Something had struck a discordant note. Taking a step forward, I directed the light towards a protrusion of grey rock emerging at forty-five degrees from the wall. There was something on the ground beside it. I moved forward, keeping the torch steady, until I saw it was a sheet of paper, lying as if impossibly blown there by a sudden gust of wind.

I picked it up. It was rough to the touch, a coarse weave. Parchment rather than vellum or the page of a book, much like the cheap papyrus tourists brought back with them from Cook’s tours of Ancient Egyptian sites. I opened it out. It was covered in scratchy, old-fashioned handwriting, more like music on a stave than printed letters. I could not read it, even when I held the parchment right up to the light.

I folded it and put it in my pocket. There would be time enough to decipher it later.

Looking up, I noticed a fissure in the rock face directly ahead. Shining the torch in front of me, I went to investigate. There was a narrow corridor, a black seam between two massive ribs of the mountain. It was exceedingly narrow and there was no way of telling how long it was, nor where it went. I felt claustrophobic merely looking at it.

But I forced myself to go in. Holding the torch above my head, I inched my way through, sideways on.

‘Take it steady,’ I said, hating the rock pressing on my shoulders. ‘Steady now.’

In the event, the conduit wasn’t so long, and after only a few paces it opened out into a small, self-contained chamber. Unlike the barren outer cave, there was evidence this cavern had been occupied. In the gloom, I could make out a few belongings, the remains of a camp, what might once have been blankets, a snatch of blue and maybe grey, hard to tell the difference in the yellow light of the torch.

‘Fabrissa?’

Why did I call her name once more? I’d already decided she could not be there. But I called out to her all the same, as though a part of me even now hoped she might be there waiting for me.

I walked closer. The torch picked out fragments of red cloth, green and grey and brown. An earthenware bowl and the stump of a tallow candle burnt down to the wick.

My pulse sped up. My subconscious mind knew what I was seeing, but I could not yet let myself face it head on. I could not accept it. Did not want to accept it.

There was something else now, an acrid smell. Like in church, when the congregation has departed but the scent of stale incense from the thurible has not yet faded. I dug in my pocket for my handkerchief and slapped it over my nose and mouth. It reeked of dried blood and oil, but even that did not completely mask the smell of the cave.

Then I heard it. The whispering. But this time, a multitude, not a single voice, the words layered one upon the other like plainsong at vespers, the harmony holding in the echo.

I stared around. There was nothing to see. Nothing moving in the shadows. Nothing. But the whispering was all around me now, behind, in front, above, a sibilance of voices weeping and calling, desperate to be heard.

‘We are the last, the last.’

‘Where are you?’ I cried. ‘Show yourselves.’

I stumbled forward, nausea rising in my throat. I was being drawn to the furthest corner of the cavern. I did not want to go, but I could not turn back.

Now another voice. Clearer. Distinct. Intended for my ears only.

‘Bones and shadows and dust.’

‘Fabrissa?’ I called out into the darkness.

I staggered on, closer to the epicentre of the sound, until my feet came to a halt of their own accord.

I needed to go no further. I didn’t want to, but I made myself look. Made myself focus on what I knew I did not wish to see. I was standing in a city of bones, men and women and children, all lying side by side, as if they had lain down to sleep and forgotten to wake.

I bowed my head, my eyes smarting, undone by the sight of the humble objects, treasures. Candles, cooking utensils, a pitcher lying on its side. Grave goods for those who had no more need of them.

At last, my head acknowledged what my heart had told me all along. Now I understood the story Fabrissa had told me, though I had not wanted to hear it before.

Had not been able to hear before.

Here were fragments of the long green robe of Guillaume Marty, scraps of something still attached to the leather belt around his waist. Here, the royal-blue robes with red stitching, rags now, worn by the Maury sisters. Here, a remnant or two of Na Azéma’s grey veil pulled up over her face. No longer people, but skeletons. Skulls half-concealed by a hood or a fold of material or by shadow, the bones glowing green-white in the pale beam of my torch.

Swallowing down the bile rising in my throat, I walked on. Now I could see the bones were clustered in groups, where families had died together. How many bodies lay here entombed? Fifty people. A hundred? More? Had anyone escaped this living death? Fabrissa said no one came back. A refuge that became a tomb. A mass tomb for the people of Nulle.

But the worst was to come. The whispering was getting louder, the pleading, crying for someone to help them. Begging for release. And joined now by another sound, superimposed on the whispering. A scratching on the stone. The rattle of bone on the rough and uneven ground. I wanted to turn back, but I could not. I could not look away for to do so would be to abandon them once more. I could not stop my ears against the horror of the voices.

I had not yet found Fabrissa, and though I prayed against all the odds that I would not, I knew it was only a matter of time. Her voice singing in the mountains, in the Ostal, the syllables and vowels smudged and indistinct, everything led to the same conclusion.

The noise intensified. Screaming now, a desperate clawing at rock and stone that could not be shifted. Not the Cers wind but, as old Breillac had said, the spirits of the dead. For countless years, the village of Nulle had lived in the shadow of the memories held in this ancient forest.

I could see shapes in the darkness, shifting and sighing, surrounding me. They would not let me be. The cave was full of movement. White shadows, sketches in the air, the silhouette of souls of the dead departed. I covered my face with my hands, knowing it would make no difference. The black parade would walk before me all the same. As I had heard them die, so too was I condemned to watch them die.