‘Great-uncle,’ Swan said. In Arabic, he said, ‘The boy is your son.’

Omar Reis met his eye. ‘Your Arabic is terrible,’ he said. He nodded very slightly.

‘Peter, let the young man go,’ Swan said.

There was a grunt, and Omar Reis’s eyes moved, just for an instant.

‘I will escort you to Constantinople,’ said the Turkish lord. He turned to Swan and bowed. ‘I thank you.’

Swan waved the Turkish lord on his way, just as he’d seen his father do a hundred times. ‘It is nothing,’ he said, in his most haughty voice.

When the Turks were gone over the side, Alessandro embraced him. ‘I think that one is on you,’ he said. ‘I owe you a fine cup of wine. And the Virgin a hundred candles of white wax.’

Giannis shook his hand. ‘You have matched wits with Satan’s own son,’ he said. ‘And the Virgin will do well from me, as well.’

The Golden Horn was perhaps the most magnificent sight that Swan had ever seen, and the towers and palaces of Byzantium – even six months after a brutal siege and sack – were the most splendid he could imagine. The tower of Galata on the Asian side was matched – or exceeded – by the golden onion domes of the great churches – some already converted to mosques. Two new minarets towered over the centre of the Palace of Blacharnae, and yet the great breaches blown in the walls by the Turkish cannon remained unrepaired.

The Turkish warships ‘escorted’ them all the way to the harbour mole for Galata. The fiction that the two ‘Smyrna’ galleys were somehow enemies of Omar Reis was thinly preserved – the two ships followed the Venetian at the distance of a few leagues, while the Turkish lord himself was always hull up, often broadside on a mere two hundred paces away.

For the last three days, they were on deck all the time – strings to bows, in harness. Swan had never worn armour four days running. The breast and back – slightly too tight – cut into him like a blade. He had constant diarrhoea, as did half the ship, and the wounds on his right leg bled yellow pus, and still he didn’t take off his armour.

The bishop’s doctor worked double tides. He proved an increasingly confident professional, and he seemed to grow in stature each day. By the time they sighted the tower of Galata, he seemed four inches taller, and six men owed him their lives.

Ser Marco was one of them. He was awake, and he screamed each day when his bandages were changed – Messer Claudio insisted on pouring vinegar on wounds. But aside from the screams, he seemed better.

They landed to a silent, hostile town. Most of the citizens were Genoese, and resented the handing-over of the town to Venice. Turkish soldiers still roamed the town.

‘It was bad here,’ Alessandro said, after he’d been ashore.

Swan had his armour off for the first time in four days. He had open sores despite his heavy leather and linen arming doublet, and a wound he’d missed altogether, a long cut that had somehow gone up under the skirts of his fauldand cut above his buttocks into the base of his back. It wasn’t bad, but it explained why he’d hurt so much.

He stank.

The pus kept coming out of his leg.

‘Fuck it,’ he said to Alessandro, and jumped into the sea.

The pain was intense, but he swam through it as the salt searched out every abrasion, every wound. It felt to him as if tiny doctors were cleaning him with tiny, sharp brushes. He swam and swam, until his arms wouldn’t support him, and then he climbed up the anchor cable, feeling curiously heavy.

Dr Claudio hauled him inboard. ‘You are the merest Empiric,’ he said. ‘You don’t know that salt water is good for wounds.’ He leaned over. ‘Let me look at your back.’

He scrubbed the wound with vinegar and then did something that hurt like fire. Swan screeched like a small girl who burns herself on a candle.

Claudio laughed. ‘Alum,’ he said. ‘Nothing cleans a wound like alum.’

The bishop disembarked and moved into a house in the town. Swan heard about his embassy from the doctor, who, as it proved, was much happier caring for the soldiers than being ignored by the churchman.

‘I was the tenth choice for the embassy,’ Claudio admitted. ‘He fancies himself a great man on an important mission, whereas the rest of us know that he’s the only man who’d take the job, and what he’s doing is a formality.’ The doctor shrugged. ‘He wanted a famous medico, and he got me.’

‘You are very good,’ Swan said.

‘You are very kind,’ Claudio said. ‘Before I threw my little loop over Ser Marco’s artery, I had never – in a practical way – manipulated a human body. One that was alive, anyway.’

‘By God!’ Swan said.

‘Oh, I have experimented on myself,’ the little doctor said, as if that made it all better.

A Turkish boat came across and the embassy loaded up to move to Constantinople. Giannis came down to the ship and took Swan, Peter and the doctor and their gear to the Turkish boat, and they were rowed across the Horn – a curious and very exacting piece of small-boat handling, given the current. Giannis chatted with the boat’s crew in Greek.

‘What do they say?’ asked Alessandro.

‘That the taxes are lower,’ Giannis said. He was angry. ‘They are traitors.’

Swan shrugged. ‘I’m not sure they are,’ he said, thinking of the Gascons and the ‘Englishmen’ of the Dordogne. ‘People need peace in order to live.’

Giannis glared at him, and he hid his smile and watched the rapid current sweep them north towards the Euxine.

It took twenty days for the bishop to present his credentials. He was outraged by the wait.

Swan was in heaven, and would happily have had the embassy delayed another twenty days.

It was like a journey to some exotic dream, peopled by the best of classical antiquity and a thousand Sir Palomides, the Saracen knight of King Arthur’s court. The Greeks looked haunted, but shops were open. If there were gaps – enormous gaps, where fifty buildings had burned, where a whole square of shops had been looted and destroyed – there were also whole quarters that looked untouched by war. Many establishments smelled of fire, and in one small square, Swan could smell the unmistakable smell of human corpses rotting. The magnificent Hagia Sophia was a stable for the Sultan’s horses. Swan paid a ducat – a staggering sum – and was allowed to walk around. Earth had been put over the floors, and men on scaffolds were painting whitewash over the mosaics of gold and lapis and marble.

He kept his thoughts to himself.

At the great doors, he met a young man who bowed to the ground. ‘You are the English prince?’ he asked.

Swan was seldom confounded by his own tales, but this gave him pause for a moment – and then he recognised the young man. ‘Idris? Son of Omar Reis?’

The handsome young man bowed again. ‘The same. I . . . owe you my life.’

Swan returned the bow. ‘Well – it proved to be a fine decision on my part,’ he said. ‘I have a suspicion that if you’d been lying in a pool of your own blood, your father would have killed us all.’

Idris shrugged. ‘Perhaps. Truth to tell, I am not my father’s favourite.’ He shrugged again. Greeks and Turks had that shrug in common. ‘Come and have coffee. Tell me how I can be of service to you.’

‘How is your hand?’ Swan asked, all contrition.

Idris bowed. ‘I can still hold a sword,’ he said. ‘One small finger – a small price to pay for my life.’

As they walked across the great square, Swan reflected briefly on how narrowly he and this other man had come to one killing the other – and now, under a change of circumstance, they sat together drinking tiny thimbles of hot, sweet liquid and talking about language.

‘I have learned Turkish, of course, and Arabic. Italian. But the most beautiful is Persian. I write poetry in Persian.’ Idris stared off into space. ‘My father disapproves of my poetry writing. And my taste in friends,’ he added with the frank bitterness of the young. ‘I went to sea to prove to him that I am a man. He is such a barbarian, he thinks that the ability to ride a horse and fight with a sword defines you. But of course, I was captured.’