The worst of the tremors occurred on their last night in the Keys. The house rocked on its foundations, as if a giant had lifted it up and was shaking it to see if anything might fall out. In the morning they found that dozens of roof shingles had come crashing down on to the patio. Also one of the exterior walls had buckled, sending plaster raining down, while the wind had whipped ashes mixed with salt water through the shattered windows and across the furniture.

They picked their way across broken glass as they packed the few belongings they needed, and climbed into Amanda’s car. Fowler didn’t look back as they drove away, even though he was leaving the beach house for ever.

There were few signs of life as they drove the short distance north to Key Largo. Palm trees and royal poinciana, whose branches had once blazed red, now bowed under the accumulated weight of volcanic ash. The streets were deserted, making Fowler wonder where his neighbours could possibly have fled. It wasn’t like there was anywhere they could possibly go that was safer.

He thought about it a while longer, then decided that the impulse driving the two of them to fly to the Far East wasn’t really so very different.

They had barely started out on their journey before they came across a van lying on its side, so that it straddled the divider. An open-topped sports car was parked haphazardly nearby, one of its doors left wide open as if its owner might return at any moment. A recorded voice emerged faintly from the dashboard, warning that the vehicle was low on power.

Amanda guided their own car around and past the second obstruction. Only once they were past did they see the bodies of a young woman and a man lying side by side, darkening pools of blood stthe tarmac around what was left of their heads.

After that encounter, they drove the rest of the way in silence. The Keys had become suddenly menacing in a way they hadn’t been before, even with the constant tremors and volcanic ashes.

In lieu of conversation, Thomas brought a news feed up on the dashboard. There were now up to half a dozen volcanoes reactivated along the spine of South America, all the way from Chile to Nicaragua. Yellowstone, too, was showing ominous signs of seismic activity, while yet more growths had been sighted emerging from the waters off the coast of Ecuador. Thermal-imaging satellites had verified several others, blossoming all along the mid-Atlantic ridge, like a cancer metastasizing throughout a living body.