In some places fires had caught, and some of the wreckage was scorched black. The fires had evidently burned themselves out without effective response.

But it was the surviving fragments of normality which were most heart-rending.

Here was a scrap of carpet, lingering beneath a stub of wall, scorched at its fringe, thick with ash. The carpet was strewn with little glass beads. At first Ted vaguely thought this was some kind of volcanic effect, but the beads turned out to be marbles, with the pictures of soccer players embedded inside. Collect all 265! And here was the skeleton of a carefully designed garden, a layout of gravel and a square of scorched earth that had been a lawn. There was no sign of the flowers that might have flourished here, the trees — fruit perhaps — were no more than charred stumps.

Some of the ruins bore pathetic messages, scraps of paper already discoloured by the sun and the billowing ash: notes pleading for Moira or Donald or Petey to meet Janet or Alec or William, at St Giles” or Waverley or the Meadow Park.

The clearing-away of the housing here provided a new, uninterrupted view of Arthur’s Seat itself, off to the north-east. But it was no longer the blunt outcrop Ted had grown up with; now there was little left but a few spiky basaltic spires, cracked and scorched, with a final venting of ash and smoke still curling into the air from its heart.

And everywhere was the cold, unearthly glint of the Moonseed, like a poison that had infected the Scottish earth, emanating from this broken-open old basaltic scab.

Up to this point they had been surrounded by the props of emergency rescue efforts: bulldozers, backhoes, tunnel borers, earth movers, some of them still working. But now they came to a place where no heavy machinery moved: where, amid the Moonseed’s silvery glow, only people picked their cautious way.

Blue had a map tucked into a plastic pouch at his waist. Now he pulled it out and showed it to Ted. It was a large-scale Ordnance Survey, marked by highlighters and pencil. “Listen up,” Blue said. “This is going to be no stroll in the country.”

“I know.”

“I bet you don’t. Here’s what we think. The Moonseed is everywhere: in the ash that coats everything, digging into every exposed chunk of bedrock, working through the subsurface layers. But there are still places we can walk. Places where the surface layers have held together. But they may be—” He was searching for the right word. “Fragile. You have meringues in this country?”

“Yes.”

“Like that. We’re going to be walking over a meringue, a thin crust of rock. Take a wrong step, and poof.” He snapped shut his fingers. That’s why there’s no heavy equipment here. We’ll follow these routes.” He indicated the highlighted trails. Other areas, Ted saw, had been sectioned off by hand-drawn blue hatching. Moonseed outbreaks.