Back when I had been stuck on my own alternate with no hope of rescue, I had learned fast to pay attention, never to let my mind drift so far that I would fail to notice the sound of wild dogs hunting me. The one time I had let my attention slip, when Yuichi and the others had hunted me across the fields and through the woods, I had come close to dying. So when I heard a faint buzzing, like that of insects, I was immediately aware of it. The sound came again, as if something had passed close by my ear.

I looked ahead of us, in the direction of the bridge, to where Lucky had run ahead. I saw that she had come to an absolute standstill just five or six metres in front of us, her body trembling with suppressed energy.

I came to a halt, and saw that Nadia and Oskar had both done the same. I felt suddenly, acutely aware of every shadow, every breeze, every sound around us.

Up ahead, the sun slipped down behind the ruins of an office building, and the darkness grew.

‘Night patrol,’ said Oskar, his voice low as he slipped his rifle from his shoulder.

Beside me, Nadia took the safety off her own weapon.

I looked around, but all I could see were the silhouettes of warehouses on either side of us.

‘Hear anything?’ asked Nadia. She spoke quietly, but her voice seemed to reverberate from the walls around us.

‘Not a thing,’ said Oskar. ‘Not any more.’

‘I definitely heard a buzzing,’ said Nadia. ‘Anyone else?’

‘Me,’ I said.

She glanced towards the river. ‘If there’s too many of them, head for the water and try and swim across.’

As if on cue, a figure emerged from the alley between two warehouses on our right. It was naked, with a sunken belly and a chest coated with thick grey hair. There was, I saw, something wrong with its head. Its skull was distended in such a way that the mouth was drawn wide in a terrifying, inhuman grimace.

‘There should be more than one,’ said Nadia, sounding surprisingly calm. ‘Anyone see the rest?’

‘Behind us,’ I said, looking over my shoulder.

They had emerged from the shadows and alleyways in their dozens. Many, though not all, had the same strange, distended features as the one blocking our way ahead.

Oskar brought his rifle up and fired over Lucky’s head, at the first creature we had seen. It staggered back as the bullets tore into its body, and it collapsed without a sound.

Then it did something I knew would give me nightmares for the rest of my life, assuming I lived long enough.