Thalius winced. 'But the scarring-'

'I'd rather wear that than the hateful thing which preceded it. Thalius, do you still believe the true purpose of the Prophecy was to change the destiny of the Church?'

That took Thalius aback. He had spoken with nobody about such matters since the day of the attempted assassination. 'So you have been thinking this through.'

'Look, I'm no philosopher,' Audax said. 'But I had that thing tattooed to my back since birth, and, on long campaigns, there was plenty of time to puzzle about its meaning. The way I see it is this: the Prophecy was a message, and somebody sent it. Now, whether it was God or demon, or even a wizard-'

'The Weaver,' Thalius said softly. 'And if Constantine had been killed, Christianity might not have been incorporated into the empire, and the capital might not have been moved east. History would have been changed-the history of the whole world, for all time.'

'Yes. Well, whoever sent back the Prophecy had a purpose. The question is, what could that purpose be? Christian symbols were written into that acrostic, the A and the O. Could it really be that the sender was trying to deflect Constantine's adoption of Christianity?'

Thalius said, 'It is what I believed at the time, I think-though others made their own interpretations of the Prophecy, and its lost promises of "freedom". Perhaps the Weaver wanted what I always wanted-strange thought! Certainly Constantine has remade the Church, and the results have been just as I feared. The bishops have taken to chastising those who won't follow the official line. The persecuted turned persecutor! Oh, I believe that thanks to Constantine the Church will live for ever. It is just that it is not my Church.'

Audax grunted. 'So if the intention of the author of the Prophecy was to "save" the Church, he or she failed.'

'Really? Perhaps you just don't want to believe, Audax, that all of the future hung on your choices in those few terrible heartbeats when you held that knife-but it did, you know. And consider this.' He shivered, an inchoate dread stealing over him. 'If history has been changed around us, Audax, if we are now living in the wrong history-how would we know?'

Audax had no answer.

'Will you tell your son about the Prophecy?'

'No.'

'You must,' Thalius said firmly. 'Ours is a remarkable family with a remarkable story. You would be depriving him of his past, his identity otherwise. Here,' he said impulsively, and he handed Audax the scroll of Claudius's memoir. 'You take this. Keep it for when he's older. Claudius was bound up with the Prophecy too, and perhaps it will help little Tarcho fill in the blanks in the story. If he's as clever as you say, he may end up understanding far more of this strange business than I, than any of us, ever did. I never even saw the Prophecy itself,' he recalled wistfully, 'not even the few lines which might have described the great upheaval of our own lives…'

Audax hesitated, then took the book. 'Very well, Thalius. I'll make sure he understands it is from you.' He looked around a cloudy sky, seeking the angle of the sun. 'Thalius, I must go. My duties-I have people to see here on behalf of the imperial heirs.'

'I understand,' Thalius said.

Audax stepped away, returning to the crowded street. 'I hope I'll see you again before I leave.'

'You know where I am-I never go far these days!'

But Audax was already lost in the crowd. Thalius, alone, empty-handed, felt his bruised belly twinge again. Moving cautiously he turned away and headed for home.

Isolde hated the idea of travelling to Britain with her father.

For one thing Isolde, nineteen years old, didn't know anybody in Rome who had even been as far as Gaul, much of which was in the hands of foederati, German 'allies' of the empire. All Isolde's friends knew about Britain was that giants had built a mighty Wall across the neck of the island to keep out capering monsters.

Nonsense, said Nennius, her father, predictably. You could tell when he got really angry because a pink flush spread all the way up his round cheeks to the shaven patch at the top of his head. Britain was just a place, its inhabitants just people, not monsters-and there was a Wall, but it had been built by Romans, not giants. Why, it was less than a decade since the British Revolution, when 'ragged-arsed rebels' had refused to pay their taxes. Britain had been detached from the empire many times before, and would no doubt be rejoined to the mother state when time and resources permitted.

'And anyhow,' he told her with a certain malicious glee, 'we're off to visit a cousin of mine, who lives on the famous Wall. We share a grandfather, cousin Tarcho and I, a slave who became a soldier called Audax, who was at the heart of the Prophecy story. And do you know how I happen to have a cousin there? Because you and I are British ourselves, daughter-a couple of generations removed, but British all the same…'

Nennius's latest scheme was all to do with a Prophecy, he said, a Prophecy lost and now partially found again, a Prophecy made but never fulfilled-a Prophecy that might have shaped the world. The key to reconstructing this puzzle, he believed, and perhaps even to recovering the Prophecy itself, lay in Britain. And so because of this old man's legend Isolde must travel beyond the empire itself.

Isolde had learned long ago that it did her no good to argue. Her whole life had been shaped by her father's ambitions, and so it was now. But as they crossed a Gaul in which you heard nothing spoken but German, and as they took to the sea in the leather-sailed boat of a blond Saxon trader with bad teeth, she felt terribly vulnerable. She was a pregnant woman accompanied only by an absent-minded old man. Not only that, her stomach churned with every tip and rock of the boat. The trader offered her a remedy, a cold tea of German herbs, but Nennius forbade her even to try it.

She tried to tell herself she was safe with her father, but she had never believed that even as a small child. He simply didn't pay enough attention to you to make you safe.

Isolde's mother had died young, and even as a young girl she had seen how unworldly Nennius was. Respected thinker and monk he might be, famous for his friendship with the great theologian Pelagius, but there were mornings when he couldn't put his own trousers on the right way round. In fact Isolde grew up thinking of herself as the adult in their relationship.

Isolde had briefly escaped when she married a young man called Coponius, of ancient Roman stock. But his good looks had belied a sickly nature. Only a month after Isolde found out she was pregnant he had been carried off by a nasty little plague, one of a series that had nibbled at the population of Rome in recent years. So Isolde had had no choice but to return home to her father, a widow at nineteen, and carrying a child. Nennius was not uncaring; Isolde knew her father loved her. But with his head forever filled with one dream or another-and now stuffed with his determination to make this extraordinary journey across the known world-there was no room for Isolde.

The boat landed at a place called Rutupiae, where a grim-looking fort loomed over a good natural harbour. The fort had seen better days. Its elaborate earthworks were clogged with rubbish, and the facing stones of its massive walls were crumbling away under the assault of the caustic sea breeze. In places they looked as if they had been robbed, quarried out.

Nennius was excited, for it was here, he claimed, that Roman invaders had, centuries ago, first set foot on the island. The only Roman from such incomprehensibly ancient history Isolde had ever heard of was Julius Caesar, and when it turned out not to have been him who had conquered Britain, she lost interest.