It came to me then with a jolt – something that I had failed to connect before. Hettie had first hummed her lullaby on the second day of my arrival – some weeks before her body washed up. Whoever summoned her had known then that she was dead, before everyone else learned the truth. And therefore they were either the one to have committed the murder or to have witnessed it.

It had to be Greer – Greer who wanted the rival for Paterson’s affection out of the way. She was more rotten than I had realized – far more so.

My thoughts weaved sickly. I hid what I had found in one of the unused rooms and stood at the window. The island was still. ‘Stay away from the dolphin,’ Mary had written, and its meaning was chilling; I must not discover what had happened to Hettie as William had. I should have stayed away, remained in ignorance – to have remained in the shadow of the truth would have kept me safe, but I now knew it all. Knew everything.

I crept along the corridor and to Mary’s room; her skin was as pale as the inside of an eggshell and I saw finally what I had been blinded to for the past days, blinded by the demonstration of her affection and my resolute belief that she was healing. I had only seen what I had wanted to see. I had not read her truly – because, beyond the thawing of her heart, she remained haunted. Hettie and William’s going had not eased Mary – her condition had worsened and the lines of anxiety were deeper, her skin more taut. Whatever preyed upon her fears remained.

I returned to my room, to the cold hearth, and watched the candle flame as if it could save me from the dread that pressed once more against my chest. I remembered those nights that Hettie came and her lullaby replayed through my head – the way her rage had cut the air. I need no longer wonder at it. I closed my eyes and saw the dream where she lay upon the bed as still as a doll. The bloody tear in her dress. I recalled Mrs Lenister’s words when Hettie had the newborn in her arms and sang – she held it like her own, she had said.

The room seemed to pall, the air to grow more chilled. From the windows cloud yellowed in the moon’s light. I saw again her reflection in the mirror – pain breaking across her face. Lamplight on her cheek as she stitched the tiny clothes.

And I knew. The knowledge left me faint – Hettie had been with Paterson’s child. I felt it as a truth. For a moment my emotions stumbled into pity and then I recalled how close Mary had come to death and I hardened my heart.

Greer had murdered not just a mother but her unborn baby as well.