From a forensics point of view, it was pretty much the perfect murder method.

Had I ever told my friends that? During a tipsy conversation over a bottle of wine? When I’d first started training with the Met as a crime scene investigator, they’d been very curious about procedure, about which TV police shows were the most realistic on the forensic side, and which the least. They thought I had the most interesting job.

But had I told them this particular fact? Maybe, maybe not. I couldn’t remember. I was more likely to have told Sean, I realised.

‘OK,’ I continued, shaking the thought off. ‘What about the fire?’ I turned to Jake and Ethan. ‘How about you two? Do you know how it started?’

Jennifer jumped straight in before they could respond, an indignant edge to her voice.

‘Hold up just a minute! Why should my boys know anything about it?’

‘They were there.’

‘All the kids were playing down there.’

‘Did you boys see anything?’

Both teenagers shook their heads, but neither of them would meet my eye.

‘Did anyone see how the fires started?’

More shaking of heads.

Jennifer said, ‘It could have been kids from the village, coming up through the gorge.’

‘All right, did anyone see any local kids down there this afternoon?’

She shrugged. ‘Can’t say I did, no.’

‘Has anyone seen any local kids down there on any day this week?’

There was a muttering of negatives from around the room.

‘Maybe we should wait for the police before we start getting into this?’ Russ said.

I turned on him, my frustration boiling over.

‘We have to pool what we know, work out how it might have happened.’

Sean took his arm off my shoulders.

‘One of the firemen found Izzy’s glasses in the clearing,’ he said. ‘Near the edge of the gorge. He had them in one of those plastic evidence bags.’

Rowan nodded. ‘I saw that too. One of the lenses was shattered.’

‘She must have lost her glasses in the confusion down there,’ Sean added, ‘and been disorientated by the smoke. She might have been running?’

There was a brittle, mechanical edge to his voice that I didn’t recognise.

Liar, I thought.

But once again, Rowan was nodding. ‘There was a lot of smoke blowing around,’ she said. ‘Maybe she just didn’t see the edge.’

It was the third time in as many minutes that Rowan had done it. Every time Sean says something, she backs him up. Why? What does that mean?

But even as I asked myself the question, an answer arrived. An answer that was supremely cynical and cruel and unfair in the circumstances, but wasn’t that what my life had turned into? This was how my mind worked now.