‘It may or may not be tied into the investigation you sent me. To be honest, it’s probably more “may” than “may not”. There’s something going on here.’

‘“Something going on”?’

‘This guy just turned up at Black Gale.’

‘All right,’ Task said. ‘I’ll call you back in a bit.’

Looking along the side of the Perrys’ house, I tried to get a sense of what had caught Mills’s attention. I walked it out: it took five seconds to go from the front to the back and yet Mills had spent much longer here – at least a minute at each of the homes. The electric meter – enclosed within a grey plastic box – was at the back of the house, the gas meter below that, but when I opened them up, there was nothing else inside. There were some empty recycling bins here too, and a group of flower pots, but whatever had been growing in them was long dead.

I moved down the slope to the Daveys’. They had some broken trellising propped against the side of their house, the rusting hulk of an old barbecue a bit further along, and the same electric and gas boxes and recycling bins. I checked the bins and boxes but, as at the Perrys’, couldn’t find anything amiss. It was the same story at Randolph and Emiline’s: their recycling bins were stationed at the side, instead of around the back like the others, but they too were empty and the gas and electricity boxes seemed fine.

I returned to the Perrys’, confused, frustrated.

There had to be something.

I dropped to my haunches next to the flower pots, trying to see if there might be something hidden under one of them. The only things I found were woodlice and weeds.

‘You got anything?’

I looked up: Healy was standing at the corner of the house. He glanced over his shoulder, past the entrance to Black Gale then out to the moors, presumably making sure we were definitely alone, and took in the granite path that connected the front of the house to the back garden, the pots, and then me.

‘No,’ I said. ‘Nothing.’

‘Something here got his interest.’

‘I know. I just don’t know …’

But then I stopped.

We both saw it at the same time: a half-brick in the wall, right at the bottom of the house, with no cement around it. It had been completely disguised by a couple of the flower pots, and was partly covered by the drainpipe, which sat flush against the edge of the brick. I shifted my weight and leaned in; Healy dropped down beside me.

‘So what have we got here?’ he said under his breath.