“The old folk call the mist the haars,” Jane said.

“It’s beautiful.”

“On a clear day you can see a long way. All the way across the Midland Valley graben from the Highlands, fifty miles or so to the north, and down to the Southern Uplands, ten miles south-east of here, beyond the coal field—”

“I’m impressed.”

“By the view?”

“By the fact that you know terms like graben.”

“You’re such a patronizing arsehole.” But this time her tone was so mild it almost sounded affectionate.

“Thank you,” he said. “So what about you? How did you get into, uh, rocks?”

“And all the other cookie-girl New Age stuff, you mean?”

“I didn’t say that.”

She pulled at a tuft of grass. “Actually, it was the Moon.”

“The Moon?”

“I read a science fiction story which shocked me. I was only ten or so — about Jack’s age, I guess.”

“What story?”

“I don’t remember the title. I think it was a Heinlein. The point was, he suggested the Moon is the way it is because of a nuclear war up there. It blasted off the atmosphere, and boiled the oceans, and killed everybody.”

He nodded. “And Tycho was just the biggest arms dump.”

“You know it. You don’t need to tell me it makes no sense.”

“I wasn’t going to.”

“It scared me to death. As I got older I started to read about all the perils we faced — still do face. Before I left school I was organizing recycling drives. I read politics and economics at university. I got into real politics later, mainly with the Greens. Not that I ever got elected anywhere. But that doesn’t pay the bills—”

“Hence the rock shop.”

“Yeah.”

“So,” he said. “You’re what we’d call a survivalist? You think that when it all falls apart we should pack up and head for the hills?”

“No.” Now she did sound offended. “Of course not. We’re human beings. We got where we are by cooperating, by helping each other. It’s just that the future is so dangerous.”

“Yep.”

“We’re going to have to be smart to survive, on any timescale you care to think about. My dad says he thinks I went a little crazy, back when I was a kid. But I think I went a little sane. It was like waking up. It seems to me that everyone else is a little crazy, not me.” She was looking out over the city, and the last of the sunlight picked out her profile, her strong nose and chin.

He said, “Maybe you’re too sane. Nobody should be burdened with too much future.”

“I’m not so tough. I’m a twentieth-century baby like everybody else. Spoiled rotten. As soon as anything serious happened, I’d run round in circles.”

“I wouldn’t be so sure.”

The light was diminishing. The Moon grew brighter, as if to compensate, and she looked up at it.

“You know,” Henry said, “the project I was working on for NASA was about going back to the Moon. Looking for water ice there. I think it’s possible there is so much ice you could actually terraform the Moon.”

“Make it like the Earth.”

“Yes. Somewhere else for people to live. But my project got canned, and we may never know about the ice. Nobody’s going to the Moon any time soon. Least of all me.”

“Would you go if you had the chance?”

He grinned. “In those ropy World War Two rockets they fly? No, sir.”

“So you’re a childless man who wants to build a new world.”

“Oh. Sublimation, you think.”

“Could be.”

“And you’re a parlour psychoanalyst. Lucky me.”

She said, “You know, after I read that Heinlein story, I coloured in maps of the Moon, figuring out where the oceans and cities must once have been.”

He nodded. “How about that. So did I. We have something in common after all.”

“I was just a kid…”

He stared up at the Moon. “It would be a beautiful thing. A terraformed Moon. It would be much brighter. A twin of the Earth. And if you were on the Moon — well, with that low gravity, it would be like something out of H.G. Wells. The First Men In The Moon.”

“Umm.” She stood up, and brushed down her dress “And people call me crazy.”

“I never did.”

“But you thought it. I know why. I run a shop where people come and pick up the rocks, trying to feel their vibrations—”

“Now they’re the crazy ones.”

“Are they?” she said mildly. “But there’s a rock in my digital watch; its vibrations keep the time. And they vibrate rocks to send laser beams, all the way to the Moon. We live in a strange world. Come on. We’d better go down before it’s too dark. Although you’ll like the Northern Lights displays we’ve been getting since Venus…”

He unfolded his legs and stood.

She led him down a different track, a path that would lead through a glacial cwm and then to a ruined chapel.

“So,” he said. “What about dinner?”

She frowned, but she didn’t immediately say no. “We just ate dinner.”

“Hell, you know what I mean. What about the weekend? I — woah.” He stopped in his tracks.

She slowed beside him. “What’s wrong?”

“What is that?” He pointed ahead.

It was a patch, on the exposed shoulder of the summit agglomerate, roughly circular. It had been hidden from where they had sat. It was, Henry estimated, two yards across. Its surface was metallic silver, flat as steel. At first it looked like some liquid — there was even a fuzzy reflection of the Moon — but he could see it was too sluggish, even for the scummiest pond.

He approached its edge.

It was a pool of some kind of fine silvery dust, or maybe rock flour. He crouched down to see. The contact with the surrounding basalt was quite clean. The rock flour seemed to be stirring slightly, almost bubbling, sluggish currents moving through its substance.

He found a loose pebble. He dropped it into the edge of the puddle. It vanished without so much as a splash.

Jane was standing over him, leaning with her hands propped on her thighs. “What do you think it is?”

He scratched his head. “I’ve never seen anything like it. Maybe it’s liquefaction. It could be some kind of magmatic event.”

“Magmatic?” She straightened up. “Come on. Arthur’s Seat has been dormant for three hundred million years.”

“I know.”

“It’s probably some kind of toxic waste,” she said.

“Maybe.”

He got up and walked off around the rim of the puddle, counting his footsteps.

Jane called, “What are you doing?”

“Measuring.”

“Why?”

“It’s an annoying thing geologists do. Can you smell anything?”

“Apart from bullshit, you mean.”

“Work with me here.”

She took a deep breath. “Nothing but the grass and the haars.”

“Nor can I.”

“Is that good?”

“I don’t know.”

“Is it bad?”

“When was the last time you were up here?”

She shrugged. “A couple of weeks.”

“And it wasn’t here then?”

“No.”

He returned to her. “Listen, do you have a bottle? Maybe makeup. Perfume or somesuch.”

“I don’t wear perfume.”

“Anything, then.”

As it happened, she did have something. It was a sample of an aromatherapy oil she’d been given by a salesman at the shop. She’d tucked it in a pocket and forgotten about it.

He took the bottle, unstoppered it, and tipped out the oil.

“Hey.”

“I’ll pay you.”

He shook the bottle dry, and then, carefully, he scraped the bottle along the top of the rock flour puddle.

When he was done, he stoppered the bottle and tucked it in a pocket of his jeans.

“What is that stuff?”

“I don’t know,” he said. “Maybe I’ll be able to find out.”

She looked around. “It really is getting dark now.”

“Yes.”

But he hesitated.

He walked to an outcrop of basalt near the pool, picked up a loose lump of rock, and hit the outcrop. He frowned at the result.

She said, “What’s wrong?”

“Did you hear that?”

“One rock hitting another? Flintstone chic—”