“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.