The bare walls of a deserted office shimmered into existence around us. Two Authority troopers were waiting just beyond the circle of field-pillars, along with someone manning a portable control rig. Exposed wiring stuck out of the walls or hung down from the ceiling, and the floor beneath our feet consisted of nothing more than bare dusty concrete. I had a feeling that the building either wasn’t finished or construction had been abandoned.

Judging by what I could see of the neighbouring buildings visible through the windows all around us, we were on the upper floors of a skyscraper. I stepped towards a window and peered through the glass at the streets far below. I could see people – real, living people – in their hundreds. The sight filled me with a kind of emptiness that was almost too much to bear.

The two soldiers quickly guided me and Yuichi up a stairwell to the building’s rooftop. I looked around, seeing Philadelphia’s rooftops spread out in every direction. Another half dozen troopers stood at various points around the roof, studying the surrounding environment through long-range sights fixed to their rifles.

A loose crowd of people stood in the centre of the rooftop, none of whom I had ever seen before. Their attention was fixed on Kip Mayer, who was talking animatedly to them. I looked around until I spotted Casey, Winifred and Haden, standing away from everyone else.

I took another look at the people gathered around Kip Mayer. They looked entirely ordinary. The majority were men in their middle age, and all wore expensive-looking suits that nonetheless had that curiously old-fashioned look that marked them as citizens of the Authority. Some had the steel-grey hair and confident, upright posture I associated with seasoned politicians, or the CEOs of multinational corporations.

A number of them, I noticed, were accompanied by women – either their wives or their mistresses, judging by how they were dressed, and the way they clung to the arms of the men. But what really took me aback was that there was also a small number of children among the group – some of them quite young. They were all well turned out in what looked to me like their Sunday best.

Yuichi had been right. They looked like nothing so much as tourists, albeit expensively and conservatively dressed ones.

I looked around, wondering at the nature of the apocalypse they had come to witness. I glanced up at the sky, and got my answer.

‘What is that, an asteroid?’ I asked Yuichi, pointing upwards, and he nodded.

I looked back at Mayer’s audience. What kind of damn fools, I wondered, would actually bring their children to a place such as this? Or did the Authority have a surfeit of rich and jaded billionaires who thought nothing of witnessing the deaths of billions just for kicks?