“It’s true we can disrupt the structures if we catch them early enough. But I don’t think whatever the Moonseed is building here is meant for this world.”

“What do you mean?”

But Blue wouldn’t answer.

He bent again, trying to collect more samples of the Moonseed structure, which he preserved in clear, fast-setting plastic.

When they were done, they walked gingerly back along the neck of land.

Ted pointed to the Cathedral on Castle Rock. “We go there.”

Blue looked at him curiously, face masked by the layers of dust and dirt on his faceplate. “Why?”

“Something I’m looking for.”

Blue shouldered his equipment. “Henry told me about your son.”

“In between porking my daughter.”

“I understand why you have come. I feel a certain — responsibility — for bringing you here.” He looked into Ted’s face. “So I feel I have to tell you this. Smell the coffee, Ted. Your son is dead. I saw him here, just before the great eruption. He is lost, here in the ruins of Edinburgh. At best you will only find his body. Probably not even that.”

“I know,” Ted said softly. “I’ve known that from the beginning.”

“Then what are you looking for?”

Ted said, “Are you coming with me, or do I go alone?”

Blue sighed. “If I abandon you, Henry will squeal like a pig stuck under a gate. Come.”

With Blue leading, they worked steadily over the shattered cityscape towards the building.

St Giles” was a great sandstone block, atypically low and squat for a Gothic cathedral, but that had evidently helped it survive; the pyroclastic flow, washing over Castle Rock, had heaped up against the eastern wall, but not breached it. Still, the stained glass windows had shattered or, it looked like, melted; and the ornate crowned tower, the Scottish equivalent of a spire, was gone.

They paused for breath.

“St Giles’,” Ted said. “Patron saint of cripples, lepers and tramps.”

“Very appropriate,” Blue said. “I am impressed it has survived at all.”

Ted pointed. “Those pillars holding up the tower are nine hundred years old. Even survived the English burning the bloody place down. They’ll last a wee while yet. Come on.”

The big wooden doors of the Cathedral had been smashed in, the shards burned. Ted and Blue picked their way over the wreckage, the scorched wood crunching under their thick-soled boots.

The roof was destroyed — debris was scattered over the aisles and altar and the rows of pews — and silvery, alien daylight streamed into the dusty interior through the gaping roof and the empty window frames. Ted stood in the doorway for a few minutes, letting his gaze follow the soothing geometry of sunbeams. As if one part of the world still worked. The Cathedral was full of light, in fact, probably brighter than it had been since the day the roof was put on. The uniform grey and black was oddly pleasing, like a charcoal sketch.