“…The Moonseed is all the way through the Moon,” she said. “That’s what this means.”

“Yes.” He rubbed his eyes. “I’m sorry. I guess that isn’t so obvious, unless you study this stuff. Yes. The Moonseed is all the way through the Moon. I kind of knew it would be,” Henry said sadly. “The assumption of mediocrity. Jays Malone wasn’t looking for Moonseed, so from the point of view of the Moonseed he landed at random, but he found it anyway. If it was here, at Aristarchus, it was going to be everywhere…

“Geena, the Moonseed works in a fractal way. The same structure regardless of scale. Whatever rock it settles in, it sets up the same kind of infestation pattern through the structure. And if you slice off a small piece of that rock, you’ll find the same structure repeated on the smaller scale, and if you slice off a piece of that, the same again… Right down to the microscopic.” He shook his head. “You have to admire the design. Cold, simple, logical. Yet with time, with the most minimal of resources, it allows the Moonseed to infest a world. The Moonseed is adapted to the universe. Perhaps the Moonseed, not we, is going to be the true master of the future…”

“You know, I hate it when you talk like that. It’s a sign of your morbid personality.”

He looked surprised. “Morbid?”

“Sure. How often would you wake me at three a.m. full of angst about death and futility? Morbid, Henry, that’s you.”

“Well, I guess I have a lot to be morbid about.”

She studied the Moon image once more. “Here’s something not in your puffball rock.” She tapped the dark centre of the image.

He rubbed his eyes. “It’s a mass anomaly at the centre of the Moon.”

“A mascon?”

“No. More dense, relatively, than that. More regular.”

“Regular?”

“It shows plane surfaces. Evidence of internal structure. It’s tens of miles across; it must be very dense. The data’s a little patchy…”

“What is it?”

He paused before replying. “Geena, I didn’t come to the Moon just to find if the Moonseed is spread right through it. I knew that must be true, if a galoot like Jays Malone could land at random and pick up a sample at his feet. All this is just confirmation.”

“Then why?”

“I had to find out why the Moon continues to exist at all. Why doesn’t the Moonseed destroy the Moon, as it did Venus? Something here has to be suppressing it. Making it inert. Oh, probably the stuff near the surface went off long ago, under the action of sunlight, but the reaction, the spread of the Moonseed, was stopped. Like everything else on the Moon, the Moonseed infestation here is old; the surface activity finished long ago.”

“Are you saying that this thing, at the core of the Moon, is suppressing the Moonseed?”

“I think so.” His eyes were fixed on nothing. “It’s the Witch in the Well, Geena. The demon at the heart of the Moon.”

“But what is it? Some geological thing?”

“No…”

He told her his hypothesis.

It came to Earth when the Solar System was young.

One day, human scientists would call it the Impactor.

It had about the mass of Mars, a tenth of Earth’s. Humans would later speculate that it was a young planet in its own right.

But they were wrong. It was not a planet.

Its heart was a dense block of matter, complex, its surface shifting, silvery. It was a hundred miles across, extraordinarily dense.

This core came trailing a cloud of silvery motes. Where the motes touched, worldlets were transformed. Raw materials rained down on the surface of the core.

It was heading for the sun. There, less than a solar radius from the young sun’s roiling surface, a great sail would be unfurled — or rather assembled, from the materials leached from the young Solar System. The sail would be almost perfectly reflective, so much so that it would have been cool, to a human touch. Humans would one day speculate about such objects, as designs for craft to cross the gulfs between the stars.

But this was no craft. To a human eye, the sail would have looked organic, its surface as structured — and as beautiful — as a young leaf.

The flood of raw sunlight would hurl the core, the sail and its attendant cloud out of the Solar System, and on to a new destination, another young system, pregnant with resources.

Perhaps that was the plan. Or perhaps the intention was different. Or perhaps there was no conscious intention.

From without, it was impossible to say.

Whatever its purpose, the object barrelled through the dusty plane of the Solar System, heading for the sun.

But there seemed to be something in the way.

“Earth,” Geena said. “You’re saying the Moonseed hive — ship, whatever — was the Impactor which hit the Earth—”

“And created the Moon. And it’s still here, deep inside the Moon.” He laughed. “Ironic, isn’t it? Without that impact — without the Moonseed — life on Earth wouldn’t even exist. But now it’s going to destroy us.”

She studied him. “Let me summarize. A massive Moonseed hive crashes into the Earth. The impact forms the Moon. The hive becomes trapped at the core of the Moon. Its cloud of, umm, nano manufacturer insects, is trapped in the Moon’s fabric. They stop their destructive behaviour because of some kind of asimov inhibitor… It sounds like something your dippy girlfriend would come up with.”

“Jane’s too sensible for this stuff. Look, it’s a consistent hypothesis. This mass concentration at the heart of the Moon, the wreckage, is actually a confirmation.”

She said, “But what about Venus? All that stuff about a black hole rocket—”

“I think that fits. If a hive gets trapped in a star’s gravity well, for whatever reason, it needs a more energetic propulsion system to escape than a solar sail.”

“But in this case—”

“In this case, the hive got itself more deeply trapped than that.” He stretched out on the floor; there were bruises on his neck, where his suit had caught him during the fall. “So I figured it out. I found what I came to find. The trouble is, it’s no use to us.”

“Why?”

“Because what is suppressing the Moonseed is something inside the wreck of a five-billion-year-old hive at the core of the Moon. Kind of out of reach, don’t you think?”

He bit into his rice cake, and chewed slowly, his expression neutral.

“So what now?”

“Now,” he said, “I do some thinking.”

“Thinking? What the hell is there to think about?”

But he wouldn’t reply. He turned back to his screen, and its light filled his eyes.

His plan, she thought. He is figuring out his plan, the one he won’t tell anyone. Whatever the hell it is, it had better be good.

She persuaded Henry he should sleep.

She watched over him, listening to the whir of the fans and extractors.

She looked out at the Moon’s moulded plains. Alone on the Moon, the only conscious mind in the world, she was driven in on herself.

Time stretched out here, in the Moon’s shallow gravity, she thought.

She touched her face, the lines there, the stiffness of her greying hair. She was, of course, ageing, as was every other member of the human race. Falling helplessly into a black future, hour by hour. And you don’t even, she thought, get a day off for good behaviour.

She checked her watch. The Rolex ticked slowly, steadily. It was 3.00 a.m., Houston time. The morbid hour.

Their human activities were regulated by the constant heartbeat ticks of their Rolexes and timers, the limits of their consumables, the working of their equipment. The chaotic clamour of Earth’s bad news. But that busy human ticking was irrelevant to the grand, slow timescales here, the time of the Moon. A day here lasted a month; she had worked for six or seven hours on the surface, and there had barely been a change even in the angle of the sunlight.