Milly honestly couldn’t read the girl; other than just after they’d found her in her parents’ crawlspace Kate Beck had maintained a kind of chilly calm, like deep water frozen over and crusted white with snow, hiding everything underneath. She was polite, even funny, but it was all surface; everything real was hidden. Perhaps unfairly on Milly’s part, she never felt she could wholly trust or like her, even though she’d done nothing wrong.

Now, though, the mask seemed to briefly drop. “Not long now,” Kate said. Milly heard a hint of fear – she wouldn’t be human otherwise – but other emotions, too, harder to decipher. Anger, hate, resignation, even acceptance; Milly glimpsed them all, but only for a moment. Then Kate turned and smiled at her, the mask back in place. “Well, just have to do our best. Anything you need doing?”

“Not right now.” All that could be done had been; only the waiting remained.

“Fair enough,” Kate nodded. “Let’s just enjoy our cigarettes, then.”

“Yeah.”

They sat, and smoked, and waited.

Ellie had no idea how deep they were now, or how long they’d been walking. The new tunnel sloped down, more steeply than the first, and began winding – a slow, descending spiral – before finally branching out. And then branching again. And again.

There were constant forks, and endless side-tunnels leading off from the main, but Madeleine, moving at a fast clip, took turning after turning without a moment’s pause, as if following an invisible rope. Like Theseus in the labyrinth, following Ariadne’s thread, except this was leading them into peril and not away. Ellie had already completely lost track of the way they’d come: she’d have to hope Madeleine could retrace their steps, assuming they lived to try, and that Madeleine’s God gave a toss about them once they’d served their purpose. Or that He was playing any part in this. Perhaps Madeleine’s visions were just a kind of immune response on reality’s part, designed to protect it from the chaos the ragged things embodied. Either way, having served their function, their survival might be of no more interest to whatever was guiding them than that of a few white blood cells would be to Ellie herself.

They passed through endless warrens with alcoves in the walls – some empty, some occupied – and two more of the dome-shaped caverns in quick succession, before the space opened up around them, so massively that Ellie felt dizzy. Far above, just within the torchlight’s reach, she saw the tips of stalactites.

“Bloody hell,” said Charlotte.

They were on a flat stone ledge that extended about twenty yards ahead of their current position, then dropped away into nothingness. A hundred feet beyond that, another ledge faced them; it too was at the top of a sheer face that led down, and down.