‘Well, she obviously got from here to there,’ said Rob. ‘If I can find her house, find where she lived, then I can skip ahead so maybe we can see her leaving.’

When he stated it like that, so calm and practical, it almost made me think it was that easy. ‘And just how would we prove that, on paper? She’s a fisherman’s daughter, she’s not likely to have left a record of her life behind.’

‘She’s no fisherman’s daughter,’ Rob reminded me. ‘Her father was the Laird of Abercairney’s son, the colonel said. Black Pate was her great-grandfather, and she herself can roam the Earl of Erroll’s castle as though she were part of his own family. For a lass so small, I’d say she had connections.’

I turned so I could see his face, the faintly stubborn jawline. ‘Do you always see the positive in everything?’

‘I see the possibilities.’ His eyes were narrowed slightly as he scanned the fields ahead. ‘They’ll soon be out of sight, if we stop here.’

I turned again, and went on walking, taking more care with my footing as the path came very close now to the edge.

Rob followed silently at first, then unexpectedly he said, ‘I was a lad of six, ye ken, when I first saw the Sentinel. Kip saw him, too – my collie, Kip – and they’d be walking side by side out in the field, and every time the Sentinel came close to me he’d smile and try to speak, except he’d speak in Latin and in those days I’d no way to understand him. But I saw him. Saw the camp as well, or bits of it. And when the archaeologists came looking for the lost Ninth Legion, I could tell them where a wall had been, or where they ought to dig. They had no proof,’ he pointed out, ‘afore they started digging. Even when they found the wall, the camp, they really had no proof the Ninth had been there. Not at first. It came in pieces, so it did, and never where they’d been expecting it. An edge of broken pottery, a coin, all scattered pieces, yet together it was proof enough to satisfy the academics.’

I was far too focused on my feet to turn around again. I asked, ‘Is this your way of saying I should have more faith?’

‘I’m saying proof may not be lying in plain sight, all neat and tidy, as ye say. And aye, it may be that we never find a document that helps, but if we dig enough we may just find enough of those small pieces to convince whoever needs convincing.’

I felt the warmth of reassurance, less because of what he’d said than from the fact he’d used the pronoun ‘we’ while he was saying it. I found I liked that ‘we’.

‘Mind how ye go,’ said Rob. I felt his hand against my elbow as he guided me a half-step further from the cliff’s edge. ‘There, that’s safer.’

Up ahead I saw a square of closely pressed small cottages. ‘Where are we now?’

‘At the Bullers of Buchan.’

I glanced at the curve of the cliff, and the white spray and foam of the water below, but it didn’t look anything like the framed photograph hanging above us at dinner last night. I was going to say so when Rob said,

‘The actual Bullers, the sea cave, is just a few steps past those cottages, see where the sign is? But we’re going this way.’ His arm brushed my own as he pointed along the short track that connected the cottages to the main road.

‘Are you sure?’

‘Aye, of course I’m sure. D’ye not trust me?’

‘It’s only that last night I thought you saw something to do with the Bullers of Buchan.’

‘I’m not sure of what I saw last night,’ Rob told me, ‘but just the now I’m seeing your Anna legging it up the road there. We can stop on the way back,’ he promised, as I took a final look over my shoulder.

Rob moved to the front when we walked at the side of the road, so that any approaching cars had to go round him first. I tried to look at the scenery. I did. We were close to the sea, still, and watching the changeable clouds chase their shadows towards the horizon should really have been more diverting, but always my gaze was pulled back to the roll of Rob’s shoulders, and the dark curl of his hair against his collar, things I had no business noticing.

Of course I found him physically attractive. I had always been attracted to him, but that didn’t change the deep divide between our lives. Up here, with nobody around, it was an easy thing for me to talk with Rob about the things he saw and heard, and let him lead me after phantoms from the past, but in public it would be a different story – I’d be too embarrassed, too afraid of everybody judging me and thinking me a fool, or worse. And Rob could never be less than he was, I knew, or hide his gifts. It wasn’t in his nature.

It would never work between us, but the logic of that knowledge didn’t stop me watching him so closely that time telescoped, so when he left the road’s edge and turned off towards the cliffs again it took me by surprise to see how far we’d come.

I could no longer see the jagged shape of Slains behind us, nor the houses at the Bullers, though farther up ahead along the coast I saw what looked to be a large town or small city.

Rob identified it. ‘Peterhead.’

But Anna and the colonel hadn’t gone the whole way there. They’d stopped, as we had, at this little sloping hollow near the road. I saw the scattering of granite stones that still stood at right angles to each other in one corner and I guessed before Rob told me that this once had been a cottage.

Rob built the walls again for me with words, their heavy sturdiness topped with a low thatched roof and pierced by little unglazed windows with their shutters left unfastened to the daylight. It was hard to think a family could have lived here, all five children and their parents, in what Rob said was a single open space inside, with swept dirt floors and whitewashed walls, no room at all for privacy. And yet I felt the comfort they had felt here, and the happiness. It resonated round me like a singing voice heard faintly on the wind, from far away, and without meaning to I placed one hand upon the stone beside me and I closed my eyes and stretched my mind towards that distant feeling.