‘If you can make it two,’ Swan said, ‘I will count it an honest deal.’

Isaac bowed. ‘I will do my best.’

Swan took his hand, and they embraced briefly.

An hour later, the boat was floating, fully loaded, in the current.

Then they all climbed up one more time, swept the floors and the fireplaces, and the women went out and dumped the ash. Everything else went into the sewers until the house was clean. Then they levered the wellhead back into position and slid down the rope.

And then Irene climbed the wall like a spider and retrieved the rope.

‘What do we do with the ladder?’ Apollinaris asked.

Swan smiled. ‘Float it with us. Not far,’ he muttered.

Swan led them along the sewers, following his map. After the first arch – foundations, he assumed of the old city walls. Passing under the arch required very careful management of the boat and the floating ladder, but they got through, mostly dry. Swan counted the wells above them, and then stopped, cut loose the ladder, and raised it on to the walkway. He grinned at Peter and offered no explanation, and they were away again in moments.

The second time they had to pass under an arch, everyone had to swim, and Nikephorus, who couldn’t, had to hold on to the back of the boat. The older man was clearly terrified, and equally clearly in control of himself to a degree that caused him to rise high in Swan’s estimation.

Irene’s figure also caught Swan’s attention.

Cold, but triumphant, they passed east almost a mile, moving easily downstream. Once they had to get out on to the walkway, empty the boat, and carry everything around an obstruction where the street above had collapsed into the cavern, but there was water on the other side, and by late afternoon, Swan found them a campsite he’d scouted in the days before. ‘Don’t go anywhere!’ he insisted. ‘Tomorrow – at sunset. Out the water gate. I’ll meet you. If I can’t come, follow Peter.’

Peter came and stood with him. ‘Is this situation covered by my wages?’ he asked.

Swan considered the question. ‘No,’ he said.

Peter nodded. ‘Would you consider me off my head if I said I want a share?’

Swan considered this, too. ‘I’m still not quite sure how I make a ducat out of this,’ he said. ‘But I couldn’t help but notice that you filled your quiver with the cardinal’s scrolls.’

‘I may be the only archer in the world with a quiver full of Aristotle, it’s true.’ Peter nodded.

‘You are a far better thief than I am,’ Swan said quietly.

‘Nonsense.’ Peter looked at the acrobats. ‘You stole the head of Saint George. I saw you.’

Swan considered denial. Then he shrugged.

Peter nodded. ‘So – I’m in for a share.’

‘So noted.’

‘What happened when you touched it?’ Peter asked.

‘Try yourself, and see. It’s real.’

Peter made a noise of derision. ‘The gold and jewels are real.’

Swan shrugged. ‘As you will. I’m off to the Venetian quarter. Don’t get lost.’

Peter nodded.

It was after dark when he dropped over the wall from the Pisan quarter into the Venetian. Shutters opened when he inadvertently overturned a handcart. He kept moving.

The inn in which the embassy were staying almost defeated him. With high walls and a gated entrance on the first level, surrounded by high buildings in the Venetian Gothic manner, it was an impenetrable fortress to a lone beggar.

He walked all the way around its block, heard voices, and found the stables – now empty. The stables didn’t have any windows, but as in buildings with ill-paid servants the world over, there was an obvious place to climb the wall. Swan was up and over and in the back yard, where once there had been a working fountain and horse troughs in a happier time.

A door was open at the back of the inn, and light seemed to flood out into the yard, brilliantly illuminating the man who stood there. He was talking to a woman who stood with her back to the light.

They blocked the door, and access.

Swan spent a weary half-hour listening to them flirt, and considering the irony – he’d crossed Constantinople undetected, and now couldn’t pass his own inn door because of a flirting couple.

‘You only want one thing, you dirty lecher,’ said the woman, with a laugh.

‘You want it too, my darling. My pomegranate,’ the man cooed.

‘My pomegranates aren’t all they were, either,’ she said. ‘Why do I even listen to your nonsense?’

‘Because the night is warm and you are beautiful—’

‘Does this work on other women, lout?’

‘There are no other women, divine one.’

She laughed. In Tom’s expert opinion, the whole thing was just a matter of time. He sat on his haunches in the shadow of the old horse yard.

‘Not here, lout!’

‘No one will come, Aphrodite.’

‘You are right that no one will come here – not me, and not you!’

‘I need you, navel of the world. Oh!’

He had her kirtle open – she had to have co-operated in that part, and Swan gave him full points, whoever he was. He was trying to get farther aboard her in the doorway. Swan cursed his hurry.

But she was of the same mind as Swan, and boxed the man’s ears.

As it turned out, her notion of privacy was the stable, which suited Swan. They made their way across the yard, one amorous exchange per step. For two people who seemed to him too old to care, they protracted the trip across the yard with more moans and caresses than he felt were possible.

But eventually, they vanished into the stables, and he ghosted across the inner yard, and in through the kitchen door.

The great inn kitchen was empty.

He stripped off his over-robe, threw it in the fire, climbed the steps with his bag on his shoulder and walked boldly to Alessandro’s room – he was now a Frank, exactly where he was supposed to be.

Alessandro was alone.

‘By the Virgin!’ he said, when Swan came in.

Swan grinned.

‘Alessandro,’ he said happily. ‘Listen, capitano. I have been to the cardinal’s house.’ He watched Alessandro’s face, but the Venetian gave nothing away.

‘Yes?’

‘I found a troupe of acrobats living there,’ he said.

Alessandro raised an eyebrow. ‘Eh?’ he said.

Either it was the finest performance Swan had ever seen, or Alessandro knew nothing.

‘They claim to be . . . spies – working for our cardinal.’ He shrugged. ‘They claim they have a message from the cardinal saying that someone would come and take them out of Constantinople.’

Alessandro nodded and stroked his short beard. ‘I see,’ he said slowly.

‘It occurred to me that they might be lying,’ Swan said.

Alessandro shrugged. ‘He has many . . . agents.’

‘So you weren’t told – perhaps when I was asleep – go and fetch the troupe of acrobats.’ Put that way, it sounded insane.

Alessandro rubbed his chin again. ‘The cardinal is most scrupulous at keeping all of us apart. Especially those he calls “day workers” from those he calls “night workers”.’

Swan nodded. ‘Did you get my note?’

Alessandro nodded. ‘I didn’t have to do anything. The bishop has already sent for the ship. Ser Marco will take us off from the quay at evensong tomorrow. Everyone is packed.’

Swan breathed a sigh. ‘Is the bishop ready? The word is he’s to be humiliated. That we will watch a procession of Christian slaves taken by Omar Reis, and see the Turkish army setting off to take the Morea.’

‘I know.’ Alessandro shrugged. ‘Truly, I fear tomorrow. The bishop is a small man, and may behave . . . badly.’

‘Am I with you tomorrow? Or not?’

Alessandro scratched his ear. ‘I think I can use your wit.’

‘Are we going armed?’ Swan asked.

‘And armoured. We are the bodyguard he is allowed in his letters.’ He crossed his arms. ‘Best we get some sleep.’

‘Yes,’ Swan said.

An hour later, he was making his way along the underground sewers, his oil lamp making a tiny glow in the immense darkness of the caverns under the silent city.