My great-aunt raises her hand. ‘Do you know what he sees?’ she asks me.

I lift my face from the book, my finger under the illustration of the man peering through the slats of the bath-house. In the foreground is the woman in the bath, her beautiful hair snaked around her white shoulders. And gleaming in the water . . . her large scaled tail.

‘Is she a fish?’ I whisper.

‘She is a being not of this world,’ my great-aunt says quietly. ‘She tried to live like an ordinary woman; but some women cannot live an ordinary life. She tried to walk in the common ways; but some women cannot put their feet to that path. This is a man’s world, Jacquetta, and some women cannot march to the beat of a man’s drum. Do you understand?’

I don’t, of course. I am too young to understand that a man and a woman can love each other so deeply that their hearts beat as if they were one heart, and yet, at the same time, know that they are utterly hopelessly different.

‘Anyway, you can read on. It’s not long now.’

The husband cannot bear to know that his wife is a strange being. She cannot forgive him for spying on her. She leaves him, taking her beautiful daughters, and he lives alone with the sons, heartbroken. But at his death, as at the death of everyone of our house, his wife Melusina, the beautiful woman who was an undine, a water goddess, comes back to him and he hears her crying around the battlements for the children she has lost, for the husband she still loves, and for the world that has no place for her.

I close the book, and there is such a long silence that I think my great-aunt has fallen asleep.

‘Some of the women of our family have the gift of foresight,’ my great-aunt remarks quietly. ‘Some of them have inherited powers from Melusina, powers of the other world where she lives. Some of us are her daughters, her heirs.’

I hardly dare to breathe, I am so anxious that she should go on speaking to me.

‘Jacquetta, do you think you might be one of these women?’

‘I might be,’ I whisper. ‘I hope so.’

‘You have to listen,’ she says softly. ‘Listen to silence, watch for nothing. And be on your guard. Melusina is a shape-shifter, like quicksilver, she can flow from one thing to another. You may see her anywhere, she is like water. Or you may see only your own reflection in the surface of a stream though you are straining your eyes to see into the green depths for her.’

‘Will she be my guide?’

‘You must be your own guide, but you might hear her when she speaks to you.’ She pauses. ‘Fetch my jewel box.’ She gestures towards the great chest at the foot of her bed. I open the creaking lid and inside, beside the gowns wrapped in powdered silk, is a large wooden box. I take it out. Inside is a series of drawers, each one filled with my great-aunt’s fortune of jewels. ‘Look in the smallest drawer,’ she says.