Swan flashed briefly on the fierce eyes – on the man parrying with his shield alone, after he’d been hit in the sword-arm. ‘I’ll be happy to testify to your bravery,’ Swan said. ‘May I have another?’

‘Effendi,’ murmured the Greek shopkeeper.

‘I owe you too much already. How can I repay you?’ asked the Turk.

Cash? A bloody great pile of ducats?

‘You could teach me Turkish,’ Swan said.

Idris made a face. ‘Perhaps,’ he said.

Next day, Swan took Peter as a guard and went to find the Jews.

They weren’t allowed to bear weapons openly, but both of them had daggers under their cloaks. Swan was sure he was followed every time they left the small inn where they were lodged in what had been the Venetian quarter. His experience in Venice had made him aware of people following him, but it was difficult here – every street was a sea of new faces; there were refugees and beggars on every corner. Still, he had an idea that the very tall, thin man he’d seen a few times was a shadow, and he tried various tricks – going down a very narrow alley he’d located in the old arcade of silversmiths, walking around by the old palace.

There was a Turkish guard on the gate of the Jewish ghetto. Swan took one look, scratched his chin, then walked back to the inn and sent a note by a beggar boy to Idris. Then he scribbled a note of his own and folded it inside Rabbi Aaron’s letter.

Idris was delighted to accompany them to the gate. He spoke a few words to the gate guard, and Swan guessed that he’d just been described as the Prince of England. He bowed, the gate guard bowed, and the three of them were allowed into the Jewish quarter.

There was damage, here – the synagogue had taken a cannonball, and Swan could see the glitter of magnificent mosaics inside. The three men stood at the entrance to the ghetto, and a pair of young men approached them.

Swan stepped forward, bowed, and asked for the house of Simon the merchant. ‘I have a letter from his brother in Venice,’ he said.

The two young men took him to Simon’s house. He was led inside, and servants bustled about. Simon was far more prosperous then his Venetian brother, the rabbi – he had a pair of Nubian slaves and half a dozen Slavic slaves, like the richest Venetians and Florentines. They were offered coffee, which was, apparently, to Turks what wine was to Italians.

Simon came, and Swan introduced himself and his two companions. He handed over the letter.

Simon bowed. ‘You will pardon me,’ he said. ‘With the siege, it is more than a year since I have heard from my brother.’ Swan saw him palm the inner note expertly and he relaxed. Simon left them for a few minutes, and they made stilted conversation and admired the calligraphy on scrolls around the walls, all of which Idris proclaimed to be Persian.

‘Except this one,’ he said, puzzling over one particularly odd scroll. The letters were both large and violent – square, almost. And yet oddly beautiful.

‘Chinese,’ said Simon, coming back into the room. ‘I thank you very much, Messer, for your kindness to an old Jew. May I be of service?’

Swan bowed. ‘I am interested in purchasing old manuscripts – old Greek manuscripts. I collect them,’ he said. ‘Your brother suggested you might help me.’ In Hebrew, he said, ‘Do you know the house in the note?’

Simon nodded. ‘I have sent a message,’ he said. ‘I expect he will come and fetch his package in person.’

‘I have it on me,’ Swan said. In Italian, he went on, ‘My poor Hebrew doesn’t go as far – could you direct me . . . to the . . .?’

Simon smiled. He waved a hand, and one of the servants led him to the neatest and sweetest-smelling jakes he’d ever seen. There was a basin of water and a basket of towels. Swan opened the basket of towels and put Balthazar’s package inside.

Then he racked his brain for the Hebrew word for ‘towel’.

Nothing came to mind. When Simon looked at him, he gave the man a small nod and mimed washing his hands.

Not even a blink of recognition.

He wasn’t going to discuss any more business with Idris present. So they spoke at random of a dozen things, asked after the family, and the business, as if he were truly an old family friend. He heard a stir in the doorway, and then there were bows.

The man who was presented – yet another Isaac – might have been Balthazar’s second son. He was the right age, and had something of Solomon’s eager friendliness. He also appeared simultaneously too friendly and ill at ease. Idris in particular seemed to excite him, and he flattered the young Turk unmercifully.

At last, Swan managed to withdraw with many protestations of future visits. They walked out the main gate, escorted by two local men, who bowed low as they passed. The janissary saluted.

Idris laughed. ‘Franks are famous for their bigotry,’ he said. ‘And you seem to be friends with everyone.’

Swan shrugged. ‘I make a habit of pulling thorns from the paws of every lion I meet,’ he said.

‘My father likes you,’ Idris said. ‘He’s going to invite you to go hunting with him.’

‘Should I?’ Swan asked.

Idris thought for a moment. ‘It would help me,’ he said.

‘Will your father give me a safe conduct in my own name?’ Swan asked. It was a little too bold, but he wasn’t sure how often he’d have access to the young Turk.

Idris smiled. ‘So – that’s what you want. Why? These old books?’

‘What would you do, to have unlimited access to Persian manuscripts?’ Swan asked.

Idris smiled. ‘You are too intelligent, and I suspect you are using me. But you saved my life – you are entitled to a little use.’ He inclined his head – very like his father – and his bearing reminded Swan that he was not always as clever as he thought he was. ‘I will ask on your behalf.’ He looked at Swan. ‘Listen – promise me something.’

Swan laughed. ‘Yes?’

‘Promise me you aren’t after this thing. This head that all the Christians want. The Sultan spoke of it today. My father has men all over the city looking for it.’

Swan looked confused, or at least, he hoped he did. ‘Head?’ he asked.

‘Christians worship the parts of dead men,’ Idris insisted. ‘In their churches. Feet. Toenails. Arm bones. This is the head of the great warrior.’

‘Maurice?’ Swan asked. He was sweating now. It wasn’t really very funny.

‘Saint George.’ Idris’s brown eyes bored into his. ‘Promise me you are not trying to steal it.’

‘Because you Turks stole it first?’ Swan asked. Sometimes, according to his uncles, it was best to attack.

Idris met his eye – and laughed.

Almost a week passed in which they weren’t allowed out of the Venetian quarter. No reason was given, and the janissaries were polite but absolutely adamant. Swan walked to the market every day, and purchased anything that caught his fancy and that he could afford. He received notes and invites from Aaron’s brother and from Balthazar’s business associates. He had to decline them – he wrote careful notes in stilted Hebrew accompanied by other notes in Italian, trying to make clear that his refusal was not his own choice.

The bishop, who had never deigned to notice him, turned after one of the messengers had gone away, and said, ‘How is it that you have friends in Constantinople? Infidel friends?’

Swan bowed. ‘Your Grace must know by now that I took young Idris prisoner in the fight on the boat,’ he said politely.

‘I know nothing of the kind. But I forbid you to have any further communication with him.’ The bishop looked at him. ‘His father is the most terrible of men – an enemy of God. The Greeks call him the son of Satan.’

Swan was about to remonstrate, but Alessandro, who was forced to spend most of his time attending the bishop, made the motion of a blade crossing his throat, which Swan took to mean he should shut his mouth.

The bishop moved on, as if, having given instructions to a servant, he had no further need to communicate. Which, as Swan considered it, was probably how the bishop viewed him.