We reached the stones. ‘Here,’ she said and crouched by the altar.

She emptied her sack and laid the contents on the ground: candles, a small bottle, a knife and a piece of black cloth.

I watched, half appalled, half fascinated whilst the moon sat unblinking in the cloudless sky. A tremor went through my fingers as the cord of her bag nearly fell from my hand and I gasped. Ailsa looked up, a flash of alarm in her eyes.

Finally, holding her scarf about the candles, she lit them and placed glass chimneys over their wicks, but even then, they flickered wildly like creatures seeking escape.

From the bottle she tipped a little liquid on to the slate where it shone and a strange, unpleasant scent made its way into the air.

‘Elspeth …’ she had been talking but I had not heard, ‘it’s time. Pass me the bag.’

It jerked as I picked it up, as if whatever was inside had moved. For a moment she did not open it but let it rest on the ground. Then she closed her eyes and began muttering. Gently, she took off her gloves and eased the knotting and, reaching in, she drew out a pebble and placed it at the corner of the stone.

‘You must turn away, Elspeth.’

I obeyed. Behind me the clatter from the sack and the sound of a click – a rustle. I tried not to listen and concentrated on the stark shapes of the cliffs ahead.

‘Turn back now.’

I turned. The altar stone was covered with the cloth and beneath that were the humped shapes of the dolls. Ailsa handed me the widows’ whistle. With horror, I wondered if she might ask me to blow it.

She began to whisper fast and furiously, and I was reminded of the first time that I had come across Mary in her nightmares and the senseless gibberish that fell from her mouth.

As she spoke, I became aware of some other voice that, although it was outside me, I seemed to hear with some inner ear, because when I listened it was only Ailsa’s that was clear on the night. At first that voice was unintelligible, but gradually it grew more persistent and I felt its will, resisting Ailsa. I grew sick and dizzy, putting my hands to my ears to block the sound, but still it continued and began to squeal and scream like a rabbit in a trap. The candles, which had grown still, began to writhe and the night opened like a mouth.

Sweat pooled on my back.