“Oh fuck,” Charlotte moaned – might even have screamed, but Ellie barely heard it and so the creatures, in their ecstasy, were unlikely to have either. More of the wall crumbled and dust boiled up, filling the cavern like smoke. Ellie choked and coughed; for long seconds she was blind, but then the silver glow shone through it.

The dust was settling. The silver flame was a brilliant column now that touched the ceiling. The Dancers knelt, facing the wall; the Pipers and the Drummers too, the Drummers continuing to beat out their rhythm.

Almost the entire cavern wall had fallen away, to reveal another wall behind it. Something it had concealed – or, perhaps, given how pieces of it still clung to the new surface – had formed a crust over. It was a dull, stonelike colour, but was neither stone nor metal. What was it, then?

Ellie had time to note a kind of seam running across the second wall, at about the same level as the Piper’s charcoal line, but only just. Because now it too began to split.

The split widened and widened; the material of the second wall crumpled and peeled away from the glistening surface that lay beneath. There was a hint of white, but most of it was a bright, vaguely luminescent gold. And, in the centre of the gold, a thick horizontal line of black.

Like the pupil of a sheep’s eye, or a goat’s –

The split closed, then opened again, even wider than before. As its lid rose, the huge caprine eye gazed into Ellie – through her – and the Piper’s tune rose to the ceiling in ecstatic triumph. In jubilation, as the first of the Sleepers woke.

A roar, thud and crash, then an explosion of light. The wedge of a snowplough blade ploughed into the creatures encircling Milly’s group. Some were knocked flying; the rest ran screeching from the headlights’ glare.

“Follow me!” someone shouted overhead. “Follow me!” It was Phil Robinson, Milly realised dazedly, leaning out of the tractor’s cabin. The Harper’s second tractor. He turned the vehicle around and accelerated across the meadow, rear lights blazing too.

The survivors staggered after him. He wasn’t going particularly fast: Milly realised he was trying to keep her and the others inside the protective glow from its lights. But he couldn’t go too slowly either, or the creatures would smash the lights. And Milly’s legs were only short; already it was pulling too far ahead of her.

Noel caught her round the waist, lifted her off her feet, and ran, teeth gritted; when they were level with the tractor, he caught hold of the doorframe. “Climb up!”

Milly wasn’t sure how, but somehow she managed. Phil, intent over the wheel, barely glanced at her as she slumped into the passenger seat. She turned, looking for Noel, but he let go of the doorframe and tumbled back into the crowd.

“Jones!” she shouted. “Jones!”