‘Which was?’ Arthur demanded. He had forgotten the lights in the sky and was staring fixedly at the Bishop.

‘His son, of course. It was ever thus, Lord. Our own God sacrificed His Son, Jesus Christ, and even demanded that Abraham kill Isaac, though, of course, He relented in that desire. But Cefydd’s Druids persuaded him to kill his son. It didn’t work, of course. History records that the Romans killed Cefydd and all his army and then destroyed the Druid’s groves on Ynys Mon.’ I sensed the Bishop was tempted to add some thanks to his God for that destruction, but Emrys was no Sansum and thus was tactful enough to keep his thanks unspoken.

Arthur walked to the arcade. ‘What is happening on that hilltop, Bishop?’ he asked in a low voice.

‘I cannot possibly tell, Lord,’ Emrys said indignantly.

‘But you think there is killing?’

‘I think it is possible, Lord,’ Emrys said nervously. ‘I think it likely, even.’

‘Killing who?’ Arthur demanded, and the harshness of his voice made every man in the courtyard turn from the glory in the sky to stare at him.

‘If it is the old sacrifice, Lord, and the supreme sacrifice,’ Emrys said, ‘then it will be the son of the ruler.’

‘Gawain, son of Budic,’ I said softly, ‘and Mardoc.’

‘Mardoc?’ Arthur swung on me.

‘A child of Mordred’s,’ I answered, suddenly understanding why Merlin had asked me about Cywwyllog, and why he had taken the child to Mai Dun, and why he had treated the boy so well. Why had I not understood before? It seemed obvious now.

‘Where’s Gwydre?’ Arthur asked suddenly.

For a few heartbeats no one answered, then Galahad gestured towards the gatehouse. ‘He was with the spearmen,’ Galahad said, ‘while we had supper.’

But Gwydre was there no longer, nor was he in the room where Arthur slept when he was in Durnovaria. He was nowhere to be found, and no one recalled having seen him since dusk. Arthur utterly forgot the magical lights as he searched the palace, hunting from the cellars to the orchard, but finding no sign of his son. I was thinking about Nimue’s words to me on Mai Dun when she had encouraged me to bring Gwydre to Durnovaria, and remembering her argument with Merlin in Lindinis about who truly ruled Dumnonia, and I did not want to believe my suspicions, but could not ignore them. ‘Lord,’ I caught Arthur’s sleeve. ‘I think he’s been taken to the hill. Not by Merlin, but by Nimue.’

‘He’s not a king’s son,’ Emrys said very nervously.

‘Gwydre is the son of a ruler!’ Arthur shouted, ‘does anyone here deny that?’ No one did and suddenly no one dared say a thing. Arthur turned towards the palace. ‘Hygwydd! A sword, spear, shield, Llamrei! Quick!’

‘Lord!’ Culhwch intervened.

‘Quiet!’ Arthur shouted. He was in a fury now and it was me he vented his rage on for I had encouraged him to allow Gwydre to come to Durnovaria. ‘Did you know what was to happen?’ he asked me.