Argante sulked in her palace. She was calling herself the Empress of Dumnonia and demanding that Sagramor and I provide her with Dumnonian guards, but she was already so thickly attended by her father’s Blackshields that neither of us obeyed. Instead we both stripped naked and lowered ourselves into the great Roman bath where we lay exhausted. The hot water was wonderfully restful. Steam wisped up to the broken tiles of the roof. ‘I have been told,’ Sagramor said, ‘that this is the largest building in Britain.’

I eyed the vast roof. ‘It probably is.’

‘But when I was a child,’ Sagramor said, ‘I was a slave in a house even bigger than this.’

‘In Numidia?’

He nodded. ‘Though I come from farther south. I was sold into slavery when I was very young. I don’t even remember my parents.’

‘When did you leave Numidia?’ I asked.

‘After I had killed my first man. A steward, he was. And I was ten years old? Eleven? I ran away and joined a Roman army as a slinger. I can still put a stone between a man’s eyes at fifty paces. Then I learned to ride. I fought in Italy, Thrace and Egypt, then took money to join the Frankish army. That was where Arthur took me captive.’ He was rarely so forthcoming. Silence, indeed, was one of Sagramor’s most effective weapons, that and his hawklike face and his terrifying reputation, but in private he was a gentle and reflective soul. ‘Whose side are we on?’ he now asked me with a puzzled look.

‘What do you mean?’

‘Guinevere? Argante?’

I shrugged. ‘You tell me.’

He ducked his head under the water, then came up and wiped his eyes clear. ‘I suppose Guinevere,’ he said, ‘if the rumour is true.’

‘What rumour?’

‘That she and Arthur were together last night,’ he said, ‘though being Arthur, of course, they spent the night talking. He’ll wear his tongue out long before his sword.’

‘No danger of you doing that.’

‘No,’ he said with a smile, then the smile broadened as he looked at me. ‘I hear, Derfel, that you broke a shield wall?’

‘Only a thin one,’ I said, ‘and a young one.’

‘I broke a thick one,’ he said with a grin, ‘a very thick one, and full of experienced warriors,’ and I ducked him under the water in revenge, then splashed away before he could drown me. The baths were gloomy because no torches were lit and the very last of the day’s long sunlight could not reach down through the holes in the roof. Steam misted the big room, and though I was aware that other folk were using the huge bath, I had not recognized any of them, but now, swimming across the pool, I saw a figure in white robes stooping to a man sitting on one of the underwater steps. I recognized the tufts of hair on either side of the stooping man’s shaven forehead and a heartbeat later caught his words. ‘Trust me on this,’ he was saying with a quiet fervency, ‘just leave it to me, Lord King.’ He looked up at that moment and saw me. It was Bishop Sansum, newly released from his captivity and restored to all his former honours because of Arthur’s promises to Tewdric. He seemed surprised to see me, but managed a sickly smile. ‘The Lord Derfel,’ he said, stepping cautiously back from the bath’s brink, ‘one of our heroes!’