The metal gate functions as a sort of air lock. Beyond lies the mine proper. Here, a different climate reigns, the air cold and clammy, tasting of mould. Only now and again a gust of warmer air catches them at intersections, furnace-hot, a relief to skin and lungs, but itself dead and heavy as lead.

They walk along rail tracks. It takes a while for this to register with Livia, and then to grow into an image: the iron bulk of a steam engine bearing down at them from out of the dark. But as they continue walking in a drawn-out procession, nothing emerges from the tunnel ahead of them, no train, no colliers, no beam of light. The tunnel itself is man-high and sloping. Steel supports bend into Gothic arches at every fourth step: cathedral cloisters built from brick and rust. Low tunnels branch off from time to time, dark gates leading into further darkness. Strange sounds carry along these shafts, the groan of steel and timber, the rhythmic whistle of moving air. They walk steadily, their heads in a stoop: gallows birds with broken necks, patrolling the warren of their afterlives to the stench of cold rot. Eight hundred and seventy feet of rock pressing down on them.

The train tracks end. Beyond, the tunnel narrows, the ceiling lowers. The steel supports give way to crooked timbers, the brick of the walls is replaced by sheer rock. And still they carry on, bent double now, humbled by the deadweight of the earth.

At long last they reach a destination, or at any rate, an ending. The tunnel widens into a long chamber, then is blocked abruptly by a pile of boulders that fills it floor to ceiling. To their right, a deep alcove yawns, not four feet in height, but some thirty feet wide and ten or so deep. Its far wall is so black it swallows the light. With a start, Livia realises this is the face of the coal seam that has been hewn away by men who must have worked it lying on their sides. Now there is no sign of recent work. Instead, the beam of Mr. Mosley’s lamp catches a series of sheets that have been hung from the supporting timbers and divide the space into narrow niches, each furnished with some dirty straw. A strange noise permeates the collapsed room, a sort of slurping, as of air sucked greedily through a half-closed ventilation trap. The mine’s breathing has grown laboured, the air heavier. It sticks to the skin like Soot.

“What happened to this place?” Livia asks.

It’s Jake who answers. “What does it look like? Gas explosion. This whole area has been closed down. The seam runs into a fault line there.” He gestures at the rock. “Not worth the trouble.”

“And that?” She points to the makeshift beds, each in its cubicle, filthy with coal dust. “Who comes here?”