‘Nimue?’ I asked, and he gripped my hand so terribly hard at the mention of her name and again he fell silent.

‘She blinded you?’ I asked.

‘Oh, she had to!’ he said, frowning at the disapproval in my voice. ‘No other way to do it, Derfel. I should have thought that was obvious.’

‘Not to me,’ I said bitterly.

‘Quite obvious! Absurd to think otherwise,’ he said, then let go of my hand and tried to arrange his beard and hair. His tonsure had disappeared beneath a layer of matted hair and dirt, his beard was straggly and flecked with leaves, while his white robe was the colour of mud. ‘She’s a Druid now,’ he said in a tone of wonder.

‘I thought women couldn’t be Druids,’ I said.

‘Don’t be absurd, Derfel. Just because women never have been Druids doesn’t mean they can’t be! Anyone can be a Druid! All you need do is memorize the six hundred and eighty-four curses of Beli Mawr and the two hundred and sixty-nine charms of Lieu and carry in your head about a thousand other useful things, and Nimue, I must say, was an excellent pupil.’

‘But why blind you?’

‘We have one eye between us. One eye and one mind.’ He fell silent.

‘Tell me about the clay figure, Lord,’ I said.

‘No!’ He shuffled away from me, terror in his voice. ‘She has told me not to tell you,’ he added in a hoarse whisper.

‘How do I defeat it?’ I asked.

He laughed at that. ‘You, Derfel? You would fight my magic?’

‘Tell me how,’ I insisted.

He came back to the bars and turned his empty eye sockets left and right as though he were looking for some enemy who might be overhearing us. ‘Seven times and three,’ he said, ‘I dreamed on Cam Ingli.’ He had gone back into madness, and all that night I discovered that if I tried to prise out of him the secrets of Ceinwyn’s sickness he would do the same. He would babble of dreams, of the wheat-girl he had loved by the waters of Claerwen or of the hounds of Trygwylth who he was persuaded were hunting him. ‘That is why I have these bars, Derfel,’ he said, pounding the wooden slats, ‘so that the hounds cannot reach me, and why I have no eyes, so they cannot see me. The hounds can’t see you, you know, not if you have no eyes. You should remember that.’

‘Nimue,’ I said at one point, ‘will bring the Gods back?’

‘That is why she has taken my mind, Derfel,’ Merlin said.

‘Will she succeed?’

‘A good question! An excellent question. A question I ask myself constantly.’ He sat and hugged his bony knees. ‘I lacked the nerve, didn’t I? I betrayed myself. But Nimue won’t. She will go to the bitter end, Derfel.’

‘But will she succeed?’