Cesare sat back and dealt another hand of piquet. ‘If only . . .’ he said. ‘God forgive me for what I’m going to say, but if only he was an aristocrat, and not a jumped-up little Romagnol peasant.’

Swan had to laugh. ‘This from you?’

Cesare spat. ‘Bah,’ he said. ‘Now that I see you are the lost Prince of England, I no longer believe that you are a true man like me, anyway.’

Then he grinned. ‘You are the bastard of a great man. I am the bastard of some roadside tryst.’

‘I’m a better swordsman, too,’ Swan said, and Cesare aimed a swipe at him that almost connected. The four of them – Alessandro, Swan, Giannis and Cesare – fenced with sword and buckler every day. Cesare was growing better by leaps and bounds, closing the gap between his ability and Swan’s even as Swan closed in on Giannis and Giannis drew fractionally closer to the gifted Alessandro.

There was little else to do. Sometimes they fenced for three hours, drank wine and ate good bread in olive oil, and fenced again. The janissaries came and watched. And wagered.

One day Alessandro paused, buckler high, and said – quietly – ‘Can your Jews cash Bessarion’s bill? We’re running low on money.’

‘Not all Jews are moneylenders,’ Swan said. He shrugged. ‘But let me ask.’

He sent Simon a note.

The next day, Simon sent back that he would be happy to change the note for cash. And the janissaries bowed, their high hats nodding on their heads. ‘You are free to visit anywhere inside the confines of the city walls,’ said Murad, the corporal.

The bishop sent word that none of them was to leave the inn.

Alessandro waved him out. ‘I’ll explain,’ he said.

‘Tell him I’m on an errand for the cardinal,’ Swan said. ‘Listen – tell me the address and I’ll take a look at the cardinal’s house.’

Alessandro wrote it down for him.

He went to the Jewish quarter first.

Isaac met him inside the gate, and walked with him to the house of Simon. ‘Your embassy is very carefully watched,’ he said. ‘You know the Sultan is contemplating war with Venice? And the Pope?’

Swan started.

Isaac went on, ‘You Franks are the most arrogant creatures on earth. Do you think that the Sultan is fooled by Venice? He plans to take all Greece – indeed, Omar Reis, who I understand you have met, is even now raising the troops to take the Duchy of Athens and the rest of the Morea.’

Swan stopped in the narrow alley. ‘I know you mean well,’ he said, although he wasn’t sure of that at all. ‘But I am the lowest member of the embassage, and I have no idea what you are talking about. I am a mere soldier.’

Isaac frowned. ‘I am informed that you are, in fact, an agent of Cardinal Bessarion.’ He met Swan’s eye. ‘Are you here for the head of Saint George?’ he asked.

Swan felt as if he had no ground beneath his feet. He couldn’t decide how to answer this accusation. He wasn’t sure why it would be a bad thing to admit to such a status.

‘Messire, I am a poor man who performed an act of friendship for Rabbi Aaron, because he has been kind to me. He is my Hebrew teacher in Venice.’ He paused and looked at Isaac to see how this speech was going down.

‘You are the friend of young Idris, the Wolf of Thrace’s youngest son. You are, I understand, an English prince come to threaten a crusade against Islam.’ Isaac all but snarled.

Swan laughed. ‘I am no prince of England,’ he said.

Isaac smiled for the first time. It was a very small smile, but it changed his demeanour and made him seem very much less threatening. ‘For such a young man of no apparent power, you have quite a few rumours surrounding you,’ he said. ‘But Balthazar said I should help you. At the same time, there’s so much happening here that I’m not at all sure that I can help you.’ He paused. ‘The Turks are ripping the city apart for the head – or so they say. It may be a pretext. Some people say the head is in Athens, and some in Corinth, and some that it is already in Rome. Some say that the Christian princes have a great army, and are luring the Sultan to his doom.’

It was obvious he had something more to say, but they had arrived at Simon’s house. Isaac bowed. ‘I will attempt to see you again. Let me say, Englishman – if you need to reach me, ask any beggar to get a message to King David.’

He nodded and walked off down the alley.

Simon received him like a visiting prince, and gave him every centime of three hundred ducats in gold.

Since it was traditional to discount a bill the further it was from its origin, Swan bowed. ‘You are a true friend.’

‘You came well recommended, and in truth, sir, I will send this bill back to my brother to be changed.’ Simon smiled. ‘I assume that you will take a packet of letters back to him?’

‘Of course,’ Swan answered. ‘If we ever leave. The Sultan seems in no hurry to receive the Pope’s ambassador.’

‘A few more days. He is preparing his armament against the Morea. He wants the campaign to begin before he receives the bishop. It is, I’m afraid, the way of the Turkish mind – to deliver an affront to Christendom while receiving Christendom’s ambassador.’ Simon shrugged. ‘Is the ambassador a man of status? Is he intelligent?’

Swan was about to answer honestly when he perceived that perhaps Simon was compromised – or perhaps, living in Constantinople, his interests were very different from Swan’s.

The world was, indeed, a very complex place. And yet, at another remove, not so very different from the world of his mother’s inn. ‘He is a famous man, in Rome,’ Swan said. ‘As for his intelligence . . .’ He shrugged. ‘He’s never said four words to me.’

Lying was best done with a tinge of truth. Uncle Dick used to say that, and it always seemed appropriate.

Simon nodded. ‘A famous man, you say?’ he asked.

Swan shrugged. ‘Even in England, I had heard of him,’ he said. Well, that was a lie. But he’d heard of Ostia.

He took the money, bowed agreeably, and escaped as soon as he could, meeting Peter at the gate.

There was a new man near the gate, an Arab in a filthy robe, whose yellow complexion and turtle-like neck would not have recommended him anywhere. His nose was large and pockmarked. His eyes were piercing and far too intelligent for the mean clothes he wore. Swan marked him with a glance, and saw him again, six streets away, emerging from an alley.

Swan walked for an hour, and the yellow-faced man was always there – not every time he glanced, but often enough that, although Swan walked past the cardinal’s house, and noted it well, he didn’t pause. Peter looked at him, and he smiled. They didn’t ask directions – all those hours learning the streets with Rabbi Aaron had had their effect – and eventually they walked past another church, and Swan made a show of being bored. In truth, he was hot and tired – the Jewish quarter was a mile from the Venetian quarter, near the Philadephion at the foot of Third Hill. And Bessarion’s house was in the palace quarter, the oldest part of the city east of the Hippodrome by the Bucoleon Palace. The area was swarming with Turkish soldiers – filthy ghazis, magnificent cavalrymen, janissaries as proud as Lucifer, who were magnificently accoutred in mail, plate brigantines, yellow leather boots and tall felt hats, and yet reminded him of the English archers he’d served with in France.

The cardinal’s house was like a tall palazzo, the portico decorated with original Greek columns from one of the ancient temples, and the windows edged in marble. A man’s head was at one of the windows, but when Swan’s apparently casual glance swept the building a second time, the man’s head was gone.

They walked home.

The moment they turned south, the yellow-faced man was no longer with them. But now Swan saw the tall, thin man from the first days – first waiting ahead of them in the street by the Hippodrome, and then watching them pass, and finally, trailing along behind them all the way to the gates of the Venetian quarter.