“Young couples. Sneaking an hour, during their shift. For privacy.” He shines his lamp in her face. “In winter mostly, when the woods are too cold.”

She feels her skin blush in the lamplight.

“That’s sordid.”

“Is it now, miss? It’s hard, waiting, when you’re in love and don’t have the money to set up a house. But you wouldn’t know about that.” He snorts, turns the light away from her, and walks over to where rockslide meets wall at the opposite end of the grotto. “You’ll have to be quiet, in any case. You’ll be staying within forty feet of them.”

She wants to ask what he means, when he suddenly disappears, swallowed up by the rock. Only his light remains visible, oddly refracted, painting shards of light onto the floor.

“Go,” Mr. Mosley encourages her. “I will help Mr. Cooper with the sick lad. This will be hard going, this part.”

ф

There is a path that leads through the wall of rubble. No, not a path: a cut, so narrow she has to squeeze through sideways, and twisting in ways that suggest that the way forward is blocked off. But somehow it never is, each twist opening to another wedge of space, in between the fallen rock. The lamp ahead gives so little light that Livia has to feel herself forward with hands and feet. Her touch is slight. She fears dislodging the rubble, causing a rockslide. It is hard to shed the feeling that she is walking to her own grave.

Then, abruptly, the rock maze ends and spills them into a low tunnel. Jake’s lamp finds a row of wooden crossbeams disappearing into the darkness, like railway sleepers in a topsy-turvy world. They don’t follow the tunnel, however, but rather branch off left, where a narrow doorway opens on a large, square room, its low ceiling held aloft by twin rows of wooden supports. Livia’s eyes take in the tables and benches, the shelves with provisions and tools, and marvels at the sudden abundance of space. Fifty people could assemble here without feeling cramped. To one side stands a hulking structure not unlike a shelf but deeper and segmented into long rectangular boxes, coffin-sized. It takes her a moment to decipher its purpose.

“What’s that for then? Don’t tell me it too is for trysts. Lovers don’t require bunk beds.” She is surprised at how cold her voice sounds. Unsympathetic. In judgement. “You are up to something. What is it?”