‘Wait!’ he said. ‘Who are you? What are you doing?’

The monk didn’t reply. Ezio could see the box as the monk stooped to pick it up again. ‘Don’t touch that! Whatever you do, don’t -‘

But the monk opened the box, and a light as bright as the sun shone forth.

Ezio thought he heard the monk give a sigh of satisfaction, before he passed out again.

When he woke again, it was morning. The horses were all gone, but with daylight, some of his strength had returned. He looked at the marble slab. It felt heavy, but it did move slightly when his arm moved under it. He looked around. Just within reach of his right hand he could see a stout branch that must have fallen from the tree at some point in the past but which was still green enough to be strong. Gritting his teeth, he picked it up and manoeuvred it under the slab. His right arm hurt like hell and started to bleed again as he wedged one end of the branch under the slab and heaved. A half-forgotten line from his schooldays had flashed through his mind: Give me a lever long enough, and I will lift the earth... He pushed hard. The slab started to move, but then his strength failed him and it fell back into place again. He lay back, rested, and tried again.

At the third attempt, screaming inwardly with pain, and thinking the muscles of his wounded right arm would tear through the skin, he pushed again, as if his very life depended on it, and, finally, the slab rolled over on to the ground.

Gingerly, he sat up. His left arm was sore, but nothing was broken.

Why the monk had not killed him as he slept, he had no idea. Perhaps murder was not part of the Man of God’s plan. But one thing was certain – the Dominican, and the Apple, were gone.

Dragging himself to his feet, he found his way to a nearby stream and drank thirstily before bathing his wound and redressing it. Then he set off eastwards, back over the mountains towards Forlì.

At last, after a journey of many days, he saw the towers of the town in the distance. But he was tired, drained by his unremitting task, by his failure, by his loneliness. On the journey back he had had plenty of time to think about Cristina and what might have been, had he not been given this Cross to bear. But since he had, he could not change his life; nor, as he realized, would he.

He had reached the far end of the bridge to the southern gate and was close enough to see people on the battlements when exhaustion finally overcame him, and he passed out.

When he next awoke, it was to find himself lying in a bed, covered in pristine linen sheets, out on a sunny terrace shaded by vines. A cool hand stroked his forehead, and pressed a beaker of water to his lips.

‘Ezio! Thank God you are back with us. Are you all right? What happened to you?’ The questions flowed from Caterina’s mouth with all her usual impetuosity.

‘I… I don’t know…’

‘They saw you from the ramparts. I came out personally. You had been travelling for I don’t know how long, and you have a horrific wound.’

Ezio struggled with his memory. ‘Something is coming back to me now… I had retrieved the Apple from Checco… but there was another man who came soon afterwards – he took the Apple!’

‘Who?’

‘He wore a black hood, like a monk – and I think… had a finger missing!’ Ezio struggled to sit up. ‘How long have I been lying here? I have to go – right away!’ he started to rise, but it was as if his limbs were made of lead, and as he moved, a terrible dizziness overcame him, so he was obliged to lie back again.

‘Whoa! What did that monk do to me?’

Caterina leaned over him. ‘You can’t go anywhere yet, Ezio. Even you need time to recover if you are to fight the battles well which lie ahead; and I can see a long and arduous journey in front of you. But cheer up! Niccolò has returned to Florence. He will look after matters there. And your other fellow Assassins are vigilant. So stay a while…’ She kissed his forehead, then, tentatively at first, his lips. ‘And if there is anything I can do to… hasten your recovery, you have only to say the word.’ Her hand began very gently to wander downwards beneath the sheets until she found her objective. ‘Wow,’ she smiled. ‘I think I am already succeeding – a little.’

‘You are quite a woman, Caterina Sforza.’

She laughed. ‘Tesoro, if ever I were to write the story of my life, I would shock the world.’

Ezio was strong and still, at thirty years old, a young man in his prime. Moreover, he had undergone some of the toughest training known to man, so it was really no wonder that he was up and about again sooner than most would have been. But his right arm had been severely weakened by Checco’s blow, and he knew he needed to work hard to recover the full strength he required to resume his quest. He made himself be patient, and under Caterina’s strict but understanding guidance, spent his enforced time at Forlì in quiet contemplation, when he could often be found sitting under the vines lost in one of Poliziano’s books, or, more frequently, in vigorous exercise of every kind.

And then a morning came when Caterina arrived in his chamber to find him dressed for travel, and a page helping him pull on his riding boots. She sat on the bed beside him.

‘So the time has come?’ she said.

‘Yes. I can delay no longer.’

She looked sad and left the room, to return not long afterwards with a scroll. ‘Well, the time had to come,’ she said, ‘and God knows your task is more important than our enjoyment – for which I hope another time will come round again soon!’ She showed him the scroll. ‘Here – I have brought you a leaving-present.’

‘What is it?’

‘Something you will need.’

She unrolled it and Ezio saw that it was a map of the entire peninsula, from Lombardy to Calabria, and all across it, as well as the roads and towns, a number of crosses were marked on it, in red ink.

Ezio looked up at her. ‘It’s the map Machiavelli spoke of. Your husband’s -‘

‘My late husband’s, mio caro. Niccolò and I made a couple of important discoveries while you were on your travels. The first is that we timed our… removal of dear Girolamo rather well, for he’d just about completed his work on this. The second is that it is of inestimable value, for even if the Templars have the Apple, they cannot hope to find the Vault without the Map.’

‘You know about the Vault?’

‘Darling, you can be just a tad naïve at times. Of course I do.’ She became more businesslike. ‘But fully to disarm our enemies, you must recover the Apple. This map will help you bring your full great task to an end.’