He was hiding under a pew. He was thin, in rags, filthy, wide eyes staring out of a sketch of a face, patchy stubble over the spittle-splashed chin. Really no more than a boy, Ted realized. He had a little food — cans and packets and bottles of water, detritus around him — and a pathetic stack of valuables, jewellery and wallets and cash.

Ted pulled off his hood. There was a stench.

“You have fouled yourself,” he said softly. “Even an animal does not foul itself. Are you, then, less than an animal?”

Blue was frowning at him, but Ted kept his gaze on the boy.

“I don’t know you.” The lad’s voice was thin, breaking, from fear and disuse.

“I know you,” Ted said. “You are Hamish Macrae. The one they called Bran.”

Bran said nothing. He shrank back beneath his pew, folding his legs against his chest.

Ted reached forward and collared him, as simple as that. From a renewed, sharp stink, it seemed as if Bran had fouled himself once more.

“Who are you?”

“Don’t you remember me, Hamish?”

“No…”

“A father, of one you led to the Seat. One of many. To his death.”

Bran was trembling, but he spoke up bravely enough. “So you found me. So what?”

Blue asked, “How did you know he would be here?”

“He stayed as close to the heart of it as he could. He was scared to run too far. There are others looking for him.”

“Too fucking right I’m holing up here,” Bran said. “Have you not heard the troopers? In the Highlands they’re already burning witches.” He looked at Ted, calculating. “I didn’t mean it. The Egress Hatch thing. I mean, I did. And I was right, wasn’t I?” He glared at Blue. “It did come from space.”

Blue rubbed his neck, through the thick fabric of his suit. “It is possible.”

“That mirror thing the Moonseed is building. It’s a solar sail,” Bran said. He smiled. “It’s obvious.”

Ted turned to Blue. “A what?”

Blue was wheezing; maybe the concentrated dust here was getting to him. He said, “A sail, to catch the sunlight and so drive a spacecraft. Perhaps that’s the purpose of the large parabolic structure the Moonseed is struggling to assemble. Others have speculated like this. The Moonseed seems to be making spaceship parts. But it is stranded, here, at the bottom of this gravity well, under all this air.”

Spaceship parts. For a few seconds, the strangeness of the thought threatened to overwhelm Ted.

“Stuck at the bottom of a well.” Ted frowned at Blue. “You sound as if you feel sorry for it.”

Blue looked up. “In a way. After all, it’s possible it means us no harm.”

“I was right,” Bran said, as if crooning. “I knew I was right. But I went a little crazy. And then, as soon as the ground started to give way—”

“You had your fun,” Ted said evenly. “Money. The girls. Didn’t you? And it cost my boy his life.”

“Are you another witch-burner, old man?”

“I don’t know. I haven’t decided.”

That seemed to renew Bran’s fear. He looked in desperation at Blue. “Who the fuck are you? Can’t you stop him?”

“I am a scientist,” Blue said. “I am here to study the Moonseed. That is all.”

Bran searched Ted’s face, his eyes huge in the dark, his face thin and weak.

“Story time’s over, laddie,” Ted said softly.

There was noise outside: whistles, shouting.

Blue looked out into the main body of the Cathedral. “I think the light is changing,” he said.

Bran tried to wriggle from Ted’s grasp. “What does that mean?”

“It means,” said Blue, “we should get out of here.”

A sound like gun-fire. Deep-throated coughs.

“Now,” Blue said.

Bran seemed dazzled by the daylight. Perhaps he hadn’t been outside for days, Ted thought. With his hand still clamped on Bran’s collar, he looked around.

A party of soldiers was running, to the west, away from Arthur’s Seat, jumping over rubble. One of them looked hurt; his mates were helping him hobble along. When they saw Ted and Blue they waved. Come on.

Smoke was rising from among the ruins atop Calton Hill.

“It is the Moonseed,” said Blue. “It has started again. The secondary vents of the old magmatic complex — Calton Hill and Castle Rock, here — we are expecting them to give way in the next cycle.”

Still grasping Bran, Ted climbed up onto a section of wall, and looked east, towards the Seat, the Moonseed pool.

The pool was glowing. Light sparked from its rim, like flashbulbs popping under a blanket. He could see the ground cracking and dissolving, sinking into the Moonseed as he watched.

“It’s spreading,” Blue said.

“Jesus,” Bran said, and he squirmed harder.

“It has been immobile for days, but now… We go,” Blue snapped. “We must get off this vent.”

“Here,” said Ted. “Take your bottles.”

For one second, two, Blue looked into Ted’s face, then Bran’s.

Then Blue nodded, evidently understanding. He grabbed the sample bottles, and ran to the west, with surprising suppleness.

Bran started shouting. “What are you doing? Shit, man, what are you doing?”

Ted shook the lad, not hard, until he stopped squealing.

When he’d turned in his results, Blue Ishiguro stripped off his Moon suit and walked back into the city. This time he walked to the east, the far side of the Seat, where the Moonseed had yet to spread.

Here, in the suburbs of Duddingston and Bingham and Northfield and Restalrig, the work of clearing the corpses hadn’t advanced so far as in the west. So he joined a party of soldiers, with little protection but their improvised cloth facemasks, as they made their way along the ruin of a street. There was no way of telling what the housing stock had been like here, but there were a lot of cellars and underground rooms, some of them new additions — Venus shelters — where people had tried to ride out the explosion.

Stiff pits, the soldiers were calling them.

They dug into the rubble. It was loose, and so there were constant falls of dust and dirt, tiny avalanches. There was no machinery, because the scientists could not guarantee that the meringue surface would support the weight of any vehicle.

So the soldiers had to use their muscles and hands. They removed layers of shattered masonry, plaster and roof beams and glass shards, all under a layer of ash and pumice, gingerly exposing an entrance. As soon as the new pit was opened, fetid air came billowing out, thick with insects. A stench, like rotting roses; after so many days, the bodies were liquefying, turning to mush down there.

In the early days, the soldiers had had to drag out the corpses, bag them up, try to identify them, take them away for burial or burning. Now, though, the solution was simpler: a corporal stepped forward, with glass facemask, and a flamethrower to hurl down a tongue of fire, the ultimate flame which these poor souls had, Blue supposed, sought to escape.

Blue Ishiguro had survived Kobe, a disastrous earthquake his science had failed to foretell. Many of his family had died there. And now, here he was, surviving again, hale and healthy, even well-fed, where so many others had died.

He was, he thought, cursed with life.

So he laboured with the soldiers for hour on hour, burying himself in the dirt and stench of it, pausing only when his body betrayed him, and dry heaves racked his stomach.