“What is it?” He picks up the jotter I hand him and starts to leaf through, then looks up with dawning realization. “Who did this?” I knew he’d be intrigued.

“Martin,” says Glen.

“This is detailed stuff.” He turns a couple of pages. “This must have taken him ages.”

“There’s photocopies of papers, and all sorts of related articles—oh, and there’s these, too.” I hold out the aerial photos. Glen explains about Martin’s theories on the memorial, and about us looking in vain for the path.

“But it’s not a path,” Ali says immediately, squinting at the photo. “It’s a negative crop-mark. You can only see this sort of thing from the air. You get positive crop-marks over old ditches and trenches, where the soil is deeper so the plants get better irrigation and nutrients, and the opposite over walls and foundations. The negative crop-marks are harder to spot; you’re lucky this photo was taken in the summer.”

“How d’you ken all that?” Glen asks him, visibly impressed.

Ali shrugs. “I watch a lot of documentaries. Mum likes them.” He glances at me quickly, as if checking my reaction to the mention of Morag, and then looks again at the photo, this time with rising excitement. “Ailsa, this might be where the kirk was. You should dig. This could really be something.”

“You two should dig. And if anything comes out of it, my dad’s name goes on it too.”

Glen and Ali look at each other. “Aye,” Glen says gruffly. “I’m game if you are, Ali.”

“Of course I’m game.” He turns to Glen. “It might be nothing, but if it is the kirk, I wonder how the loch came to be there? Was a river maybe diverted? And if so, when?”

I’m about to leave them to it, but I find myself turning back. “You should try and get up by the falls, too. In case he was right about the memorial.” I showed Fi the entry in my father’s notes only a few days ago. Callum McCue; what a funny coincidence, I said casually. I don’t know what reaction I was expecting, but she simply nodded.

“Aye, lass, if it’s safe,” says Glen agreeably, his eyes still on the photos.

I bite my lip to keep from insisting, but Ali has caught a glimpse of my face. “We will, Ailsa,” he says quietly. “I’ll find a way.”

I leave them to it.