Mad, I thought, mad and heartbreakingly beautiful, as beautiful as Ceinwyn had once been, though this girl, unlike my pale-skinned and golden-haired Ceinwyn, was black-haired and her skin was sun-darkened. ‘Why do they call you Olwen the Silver?’ I asked her.

‘Because my soul is silver, Lord. My hair is dark, but my soul is silver!’ She spun on the path, then ran lithely on. I paused a few moments later to catch my breath and stared down into a deep valley where I could see a man herding sheep. The shepherd’s dog raced up the slope to gather in a straggler, and beneath the milling flock I could see a house where a woman laid wet clothes to dry on furze bushes. That, I thought, was real, while this journey through the hills was a madness, a dream, and I touched the scar on my left palm, the scar that held me to Nimue, and I saw that it had reddened. It had been white for years, now it was livid.

‘We must go on, Lord!’ Olwen called me. ‘On and on! Up into the clouds.’ To my relief she took her dress back and pulled it over her head and shook it down over her slim body. ‘It can be cold in the clouds, Lord,’ she explained, and then she was dancing again and I gave the shepherd and his dog a last rueful glance and followed the dancing Olwen up a narrow track that led between high rocks.

We rested in the afternoon. We stopped in a steep-sided valley where ash, rowan and sycamore grew, and where a long narrow lake shivered black under the small wind. I leaned against a boulder and must have slept for a while, for when I woke I saw that Olwen was naked again, but this time she was swimming in the cold black water. She came shuddering from the lake, scrubbed herself dry with her cloak, then pulled on her dress. ‘Nimue told me,’ she said, ‘that if you lay with me, Ceinwyn would die.’

‘Then why did you ask me to lie with you?’ I asked harshly.

‘To see if you loved your Ceinwyn, of course.’

‘I do,’ I said.

‘Then you can save her,’ Olwen said happily.

‘How did Nimue curse her?’ I asked.

‘With a curse of fire and a curse of water and the curse of the blackthorn,’ Olwen said, then crouched at my feet and stared into my eyes, ‘and with the dark curse of the Otherbody,’ she added ominously.

‘Why?’ I asked angrily, not caring about the details of the curses, only that any curse at all should have been put on my Ceinwyn.

‘Why not?’ Olwen said, then laughed, draped her damp cloak about her shoulders and walked on. ‘Come, Lord! Are you hungry?’

‘Yes.’

‘You shall eat. Eat, sleep and talk.’ She was dancing again, making delicate barefoot steps on the flinty path. I noticed that her feet were bleeding, but she did not seem to mind. ‘We are going backwards,’ she told me.