“I’m not equipped for a hike,” she said.

“You’ll be fine.” Ted’s grizzled pillar of a head protruded from the neck of his thick all-weather rad-proof jacket. His legs worked steadily, hard and mechanical, and his breath was deep, calm and controlled.

It was quiet, she noticed absently. There was the moan of the wind through the grass, the distant wash of traffic noise from the city. But that was about all.

What was missing?

She stopped. “Bird song,” she said.

“What?”

“I can’t hear any bird song. Can you? That’s why it’s so quiet.”

He nodded, and walked steadily on.

A few dozen yards further, Ted halted. He pointed up the slope, towards the grey, brooding pile of the Chapel, where it sheltered under the crag, still a couple of hundred yards away. “There,” he said. “What do you make of that?”

“What?”

“Don’t they teach you observation any more? Look, girl.”

She looked, and stepped forward a couple more paces.

Under scattered fragments of broken orange-brown igneous rock, under green scraps of grass and heather and moss, there was a silvery pool. It clung to the outline of the crag, as if the rock had been painted.

“Now,” said Ted, “this used to be solid rock. I wouldn’t step much further.”

“Why not?”

He bent and picked up a chunk of loose rock. With a reasonably lithe movement he threw it ahead of her, into the dust.

It sank out of sight, immediately, as if falling into a pond.

“Wow,” she said. “How far does this go?”

“I don’t know. There seem to be other pools, up around the summit, and then the odd outbreak like this one. Like something coming through the rock, somehow.”

“Has anybody been hurt up here?”

“Sunk in the dust, you mean? Nothing’s been reported, so far as I know.”

She thought. “No, it hasn’t.” She’d have heard. “So what’s caused it?”

“Well, hell, I don’t know. I’m no scientist. I’m just an observant copper, like you. What else do you notice?”

She looked around, trying to take in the scene as a whole. Her skirt flapped around her legs, irritating her.

“I think the profile has changed. Of the Seat.”

“Very good. On the slope we’re standing on, which is no more than six or eight per cent, I’d say there has been a slip, overall, of ten or fifteen feet. And in the steeper slope at the back of the Dry Dam, for instance, it’s a lot more than that.”

“You think so?”

“You can hear it. Especially at night. Rock cracking. Little earthquakes, that shake the foundations of your house.”

She stepped forward, cautiously; she had no desire to imitate the fate of Ted’s pebble. When she’d got to where she judged the edge of the dust pool to be — still standing on firm, unbroken basalt, maybe three feet from the lip of the dust — she crouched down.

The dust was fine-grained, like hourglass sand. It seemed to be shifting, subtly, in patterns she couldn’t follow. It was more like watching boiling fluid than a solid.

She thought she could smell something. Perhaps it was sulphur, or chlorine.

Occasionally she thought she could see some kind of glow, coming from the dust where it was exposed. But it was sporadic and half-hidden. She’d once flown over a storm in a 747; looking out of the window, at lightning sparking purple beneath cotton-wool cloud layers, was something like this.

“Come on,” Ted said. “I need to show you something else.” He headed down the slope, and started walking around the pool.

She straightened up carefully, and went to follow Ted.

She said, “You think this has something to do with the loss of the lines? The TV and gas and phone—”

“I wouldn’t be surprised,” he said mildly. “Can’t say how far underground it spreads, how far it has got.”

“But if there are land slips going on, some kind of subsidence—”

“You could get line breaks. Yes. There have been scientists up here, poking and prodding away. There’s an American chap my son works with… But they’re just recording, measuring. I think someone should be doing something. Taking it a bit more seriously.”

They climbed around the crag. They were paralleling the edge of the funny dust, Morag saw. It made for a rough circle, she supposed, patches of it draped across the breast of the land. But the edge of the circle was rough and irregular; in some places necks of the dust and broken ground came snaking down the hillside, perhaps carried there by some slip or a fault in the basalt, and they had to descend to avoid it.

Now, Morag heard singing. I Wish I Was A Spaceman / The Fastest Guy Alive… It sounded like a TV theme tune.

“Good Christ,” Ted said. “I haven’t heard that in thirty years.”

“It sounds like kids” TV.”

“So it is, my dear. But long before your time.”

They entered the Dry Dam and came on a line of people. They were dressed in some kind of purple uniform, and they were sitting in a loose circular arc that embraced the hillside, and they were singing.

I’d Fly Around The Universe…

They were mostly slim to the point of thinness. They didn’t seem cold, despite the paucity of their clothes, the keenness of the wind up here. They were singing with a happy-clappy gusto.

There was a boy standing at the centre of the loose arc, age eighteen or so, skinny as a rake. When he saw Ted and Morag approaching he got to his feet, a little stiffly, and approached.

“Welcome,” he said. “My name is Bran.”

“Now then, Hamish,” Ted said stiffly.

Morag glanced at Ted. “You know this gentleman?”

“Used to.”

“Would you mind telling me what you’re doing up here, sir?”

“Watching the Moonseed, of course,” Bran-Hamish said.

“The Moonseed?”

“All this started just after that Moon rock was brought to the university. And Venus, of course. Fantastic, isn’t it? Two thousand years of waiting—”

Morag walked forward. The members of the group, still singing, looked up at her. Before each of them there was a small cairn, of broken fragments of basalt. When she looked further up the slope, she saw broken ground, exposed silver dust, loose vegetation floating on the dust. Another pool. The smell of ozone was sharp.

“Every morning we mark it with a cairn,” Bran said. “And every morning it has come further down the slope.”

“You’re a fruitcake,” Ted said bluntly.

“Maybe,” Bran said amiably. “But at least we’re here. Where are the scientists, the TV crews, the coppers—”

Morag thought she could answer that. She imagined her own desk sergeant fending off nutcase reports from dog-walkers, about an oddity no one could classify.

Morag frowned, pointing up the slope. “Where are the other cairns? The ones from yesterday, and the day before.”

“Gone,” Bran said simply. “Consumed, every morning. Like your fry-up breakfasts, Ted.”

Morag straightened her cap. “Sir, I think you’d be advised to come away from here.”

Bran spread his hands. “Why? Are we breaking the law?”

“No. And I can’t compel you to move.”

“Well, then.”

She pointed to the dust. “But it’s obviously not safe.”

“We’ve never been safer. Not since the Romans came have we been so — close.”

Ted pulled a face at Morag. “I told you. Fruitcake.”

Bran-Hamish just laughed, and resumed his seat with the others.

Morag and Ted walked away.

“Well,” Ted said. “Now you’ve seen it. What are you going to do?”

Morag hesitated.

She’d never faced anything like this before, in her brief police career.

She’d had some emergency training, at police college and since joining the station, with the council’s emergency planning people. It had all been rather low-key, underfunded and routine. Britain was a small, stable island. Nothing much in the way of disasters ever happened.

Morag had not been trained to handle the unexpected.

“I can’t see this is any kind of criminal matter. And this isn’t yet an emergency.”