Time seemed to stretch, flowing like mercury. Henry knew that if the burn was too short, they would finish up on some weird, perhaps unrecoverable orbit. But if the burn was even a few seconds too long then instead of missing the Moon by that crucial sixty-nine miles or so, they would drive into its eternal surface, creating one more crater among billions.

It was the longest four minutes of his life.

“Burnout coming up,” Geena said. “Chamber pressures dropping to fifty psi… three, two, one.”

The engine thrust died in a snap; the vibration and noise disappeared, and Henry was thrown forward against his straps.

The fires around George Square seemed to be growing, not diminishing, and still the jolts and aftershocks came. Jenny sat squat on the ground, her hands spread out, not daring even to stand.

In one place, in the west of the city, there was a kind of fountain, of steam and fire, that reached hundreds of feet into the air. Great glowing rocks shot out of it, and where they landed, like bombs, new fires started. A volcano, she guessed, right here in the middle of Glasgow.

People were gathering in the Square, in ones and twos or small groups. Some were burned, or were nursing damaged limbs or heads, crudely bandaged, or were carrying other injured.

Some of them had stories, and Jenny listened in horror.

There was the woman who had come across the Glasgow Bridge, to flee the fires on the south bank. The bridge had collapsed, and the woman, with dozens of others, had ended up creeping across a single iron beam. But there had been a panic, a rush, crushing and suffocating, and fifty or sixty had been sent headlong into the waters of the Clyde. When she looked down, the woman saw maybe a hundred people in the water, some swimming or clinging to flotsam, some already dead. There were small boats trying to pick up survivors, but their task seemed hopeless.

Here was a man who had seen Argyle Street crack right open, and fill up with a bizarre mix of rushing water and a wall of fire, from burst mains; the crowds had fled through streets that, even where intact, were jungles of downed power lines, bricks, rubble, shattered glass and felled lampposts and burning cars.

Another woman barely escaped when the motorway bridge collapsed, steel reinforced concrete twisting like plasticine.

An elderly woman had been asleep in her bed, when her high-rise block collapsed. Her first floor flat had become the ground floor; the lower level had telescoped down to eighteen inches. When she clambered out, dazed, she found people trying to mount a rescue operation, shimmying down fire hoses, people screaming and crawling over each other.