There were no lights, and although the path we trod was clear and level, I had to scurry to keep up with Pierce, and feared that I might at any moment trip or slip amid the fallen masonry. But the plume lit our path, or rather the fire beneath it did, a beacon in the heart of the park. Our destination was a rushing geyser of fire, cupped in the black, skeletal hand of a car frame.

The burning car was parked in an uneven clearing where paths converged. We slowed, feeling the heat on our faces. As we came into the glade, a tyre blew out and the car’s body shuddered, coughing up a rush of sparks. All around the naked branches danced and snatched, catching the light of the somersaulting flames. A wet slap of combusted petrol hit the back of my throat and I gagged, feeling again the damage Pierce’s arson had done to my lungs.

Another tyre blew, putting a knot in the plume of smoke. We had entered the clearing, but stayed at its edge, near the line of tombs and trees, circling the car.

‘The fire’s just started,’ Pierce said. ‘Only a minute or two ago.’

‘Should we call someone?’

Pierce was staring into the fire, but his gaze was askew – he was not looking at the funeral pyre of the car, but through it, to the far side of the clearing. The oily light of the blaze had saturated my eyes and at first I took the activity he was watching to be the dancing ghosts of the flames. But it was not – it was people, moving out before the trees. They had tracked us as we circuited the clearing, and now stood in the mouth of the path we had come by, blocking our return: three young men, looped together by volatile youthful energy, jostling and striding and laughing, and looking at us.

Together, thinking the same, Pierce and I turned our heads the other way, to the next path from the clearing. And there were more, another four clustered around a bench, two men and two women, all young, full of strut and angry cheer. Two of this second group broke away and began to approach us. Quite by chance, we were caught in pincers.

Horrid familiarity crept up inside me.

It was happening again.

I looked at Pierce, hoping to see some of the reassuring confidence I recalled from our earliest acquaintance, the good-for-all-occasions cockiness and charm that made him cheek police officers and lad it up with photographers. His face was hollow with horror, mouth a shapeless scrawl.

‘Hey! Hey!’ the nearest youth said, jutting his chin at us. He was, like his companions, wearing a chunky puffer jacket, and it was impossible to place his age – mid-twenties, though the margin of error could be a decade wide each way. Everything in his stance and step was a challenge to us. Though they were dressed almost identically, the trio on that side were racially diverse; the advance party was black, the two behind them white and Asian.