Blood spurted and streamed from Francesco’s wounds and Ezio was covered in it, but he would have gone on stabbing the dying man if Mario’s words had not then come back to him: ‘Do not become the man he was.’ He sank back on to his heels. Francesco’s eyes still glittered, though their light was fading. He was muttering something. Ezio leaned low to listen.

‘A priest… a priest… for pity’s sake, fetch me a priest.’

Ezio was deeply shocked, now that the fury within him had abated, at the savagery with which he had killed. This was not in accordance with the Creed. ‘There is no time,’ he said. ‘I will have a Mass said for your soul.’

Francesco’s throat was rattling now. Then his limbs stiffened and shook as he reached his death throes, his head arching back, his mouth open wide as he fought the last impossible battle with the invincible foe whom we all have to face one day; and he sank down, an empty bag, a slight, shrunken, pallid thing.

‘Requiescat in pace,’ murmured Ezio.

Then a new roar arose from the square. Across from the south-west corner fifty or sixty men came running, led by a man Ezio recognized – Francesco’s uncle, Jacopo! They bore the Pazzi banner aloft.

‘Libertà! Libertà! Popolo e libertà!‘ they shouted as they came. At the same time the Medici forces streamed out of the palazzo to meet them, but they were tired and, as Ezio could see, outnumbered.

He turned back to the body. ‘Well, Francesco,’ he said. ‘I think I have found one way in which you can repay your debt, even now.’ Quickly, he reached under the corpse’s shoulders, hoisted it up – it was surprisingly light – and carried it to the balcony. Here, finding a lanyard from which a banner hung, he used the length of rope to fasten around the old man’s lifeless neck. He quickly attached the other end to a sturdy stone column, and, summoning up all his strength, raised it high, then tossed it over the parapet. The rope paid out, but suddenly jerked taut with a snap. Francesco’s limp body hung, toes pointing listlessly at the ground far below.

Ezio hid himself behind the column, ‘Jacopo!’ he called in a voice of thunder. ‘Jacopo de’ Pazzi! Look! Your leader is dead! Your cause is finished!’

Below, he could see Jacopo look up, and falter. Behind him, his men, too, hesitated. The Medici troops had followed his gaze, and now, cheering, they were closing in. But the Pazzi had already broken ranks – and were fleeing.

In a matter of days, it was all over. The power of the Pazzi in Florence was broken. Their goods and property were seized, their coats-of-arms torn down and trampled. Despite Lorenzo’s appeals for mercy, the Florentine mob hunted down and killed every Pazzi sympathizer they could find, though some of the principals had fled. Only one who was captured obtained clemency – Raffaele Riario, a nephew of the Pope, whom Lorenzo considered to be too credulous and ingenuous to have had any serious involvement, though many of the Duke’s advisers thought that Lorenzo was showing more humanity than political astuteness in his decision.

Sixtus IV was furious, nevertheless, and placed Florence under an interdict, but he was powerless otherwise, and the Florentines shrugged him off.

As for Ezio, he was one of the first to be summoned to the Duke’s presence. He found Lorenzo standing on a balcony overlooking the Arno, watching the water. His wounds were still bandaged but they were healing, and the pallor had left his cheeks. He stood proud and tall, and fully the man who had earned the soubriquet Florence had bestowed on him – Il Magnifico.

After they had greeted one another, Lorenzo gestured towards the river. ‘Do you know, Ezio, when I was six years old, I fell into the Arno. I soon found myself drifting down and into darkness, certain that my life was at an end. Instead, I woke to the sound of my mother weeping. At her side stood a stranger, soaking wet and smiling. She explained to me that he had saved me. That stranger’s name was Auditore. And so began a long and prosperous relationship between our two families.’ He turned to look at Ezio solemnly. ‘I am sorry that I could not save your kinsmen.’

Ezio found it hard to find words. The cold world of politics, where distinctions between right and wrong are too often blurred, was one he understood but rejected. ‘I know you would have saved them if it had been within your power,’ he said.

‘Your family house, at least, is safe and under the city’s protection. I have put your old housekeeper, Annetta, in charge of it, and it is staffed and guarded at my expense. Whatever happens, it will be waiting for you whenever you wish to return to it.’

‘You are gracious, Altezza.’ Ezio paused. He was thinking of Cristina. Might it not be too late to persuade her to break her engagement, marry him, and help him bring the Auditore family back to life? But two short years had changed him beyond recognition, and he had another duty now – a duty to the Creed.

‘We have won a great victory,’ he said at last. ‘But the war is not won. Many of our enemies have escaped.’

‘But the safety of Florence is assured. Pope Sixtus wanted to persuade Naples to move against us, but I have persuaded Ferdinando not to do so; and neither will Bologna or Milan.’

Ezio could not tell the Duke of the greater battle he was engaged in, for he could not be sure if Lorenzo was privy to the secrets of the Assassins. ‘For the sake of our greater security,’ he said, ‘I need your permission to go and seek out Jacopo de’ Pazzi.’

A cloud crossed Lorenzo’s face. ‘That coward!’ he said angrily. ‘He fled before we could lay hands on him.’

‘Do we have any idea where he might have gone?’

Lorenzo shook his head. ‘No. They’ve hidden themselves well. My spies report that Baroncelli may be trying to make his way to Constantinople, but as for the others…’

Ezio said, ‘Give me their names,’ and there was something in the firmness of his voice that told Lorenzo that here was a man it might be fatal to cross.

‘How could I ever forget the names of my brother’s murderers? And if you seek and find them, I shall be forever in your debt. They are the priests Antonio Maffei and Stefano da Bagnone. Bernardo Baroncelli I have mentioned. And there is another, not directly involved in the killings, but a dangerous ally of our enemies. He is the Archbishop of Pisa, Francesco Salviati – another of the Riario family, the Pope’s hunting dogs. I showed his cousin clemency. I try not to be a man like they are. I wonder sometimes how wise I am in that.’