But I remember, even before I fumble for the bedside lamp switch. I’m in a clifftop blackhouse on the edge of the world. And the sound – the sound that has raised the hairs on my skin and scalp; that has set my heart beating so hard I can feel its pulse in my fingers and toes – is not nurses on night rounds or the swish of fire doors. It is here.

I hear it again close to the window. Quick, light taps against the glass. And then muffled, louder taps getting closer. I listen to their progress along the wall towards the fireplace, and I draw my knees up against my chest. I think of the narrow paved path that encircles the cottage. Could it be sheep? But those taps don’t sound like hooves. They sound like steps. Light and fast. As though someone is on tiptoe.

I almost scream when something scrapes too loud, too close, against the kitchen wall. It pauses, and I spin round in the bed, ears rushing with white noise as I strain to listen. When it starts up again – a scratching like something pressed against and dragged along the stone outside – I lurch out of bed, my hand over my mouth. The door to the mudroom is open, and I nearly scream again when it reaches the door, starts tapping on the small inset window. Another longer scrape of stone, and then the bathroom window. I think of bòcain and thin places. I think of dead birds with empty oval eye sockets. The hooded crow is often referenced in Celtic and Norse mythology and ritual. I think of someone watching from the darkness. Worst of all, I think of Robert Reid.

I back into the centre of the room, shaking, shivering, my breath ragged and short. I spin in my own clockwise circle as I follow the resumed fast steps and loud scratching. Round the northeast corner and the box room, the long front of the blackhouse, back towards the west wall and the fireplace. Someone is running around and around the cottage on their tiptoes and tapping the windows, their body pressed up against the stone walls.

I’ve no idea what to do. So instead I do nothing but continue to spin around and around, my fingers against my mouth as I track the progress of those sounds. Faster, louder. Circuit after circuit, until I can’t stand it any more and run towards the door. There I hesitate – my shaking fingers inches from the long curtain hiding the door and its little inset window. The scratching and tapping is at the west wall again, heading for the corner fast. I wrench back the curtain with a breathless yip and lurch up onto my tiptoes to look out the window. There’s nothing but darkness. The sounds have stopped too, and this I find most unnerving of all.

Until something – someone – knocks at the door so hard, it shudders in its wooden frame.