Belisarius grunted. 'It seems to me heretical to put limits on God.'

'Perhaps. Our friends in the village would think differently altogether. To them we humans are woven into the tapestry of all things, the tapestry of time. Every event that is to come grows out of all that went before. You have free will, to some extent, but only within the greater embedding of the universe. In our German tongues, the word for "weave" has the same root as that for "fortune". Gewaef and gewif. Only the Sisters of the Wyrd, who endlessly weave their tapestry, have greater power.' He winked at Belisarius. 'In such a world prophecy is possible, of a sort, but only in that one may dimly guess at the continuation of the pattern in the tapestry from the lines of its threads. No god could see the future, not even Woden, for the future does not exist. The future is a process of becoming from the present, as a tapestry emerges from the loom.'

'But you do not believe in the Sisters of the Wyrd.'

'Of course not.'

'Then who made your prophecy? I don't mean Isolde-who poured these words into her head?'

Boniface closed his eyes and smiled. 'The author of this document – man or angel or demon-is said by legend to inhabit not the root of the tree of destiny but its topmost branches – not the past but the future. He is known as the Weaver. And he has a plan…'

Belisarius was not impressed by this vague mysticism. But his attention was drawn to the next stanza, the fifth. For if Boniface was right, this was the first of the remaining stanzas which described the future. He read it aloud:

The Comet comes/in the month of May.

Great Year's midsummer/less nine of seven.

Old claw of dragon/pierces silence, steals words.

Nine hundred and twenty-one/the months of the fifth Year…

'This sounds gloomy, Dom Boniface. What can it mean? A dragon is a pagan symbol, hardly appropriate in a Christian poem. And what is this silence?'

Macson's eyes widened. 'There is a Great Silence here in this holy house. You've spoken of it yourself, Domnus, the Great Silence of your monkish lives. Is it possible this dragon, whatever it is, will disrupt your lives?'

Boniface did not respond. But the three of them, Belisarius, Aelfric and Macson, shared glances.

Belisarius said, 'If this is true, the question is when.' He looked again at the Menologium with its lists of numbers of months. 'We have that specific date, when your Cuthbert was called by his King. From that we should be able to work out the date of your fifth stanza.' He stared at the words. 'Nine hundred and twenty-one months: how many years is that?'

'Don't try,' Aelfric warned. 'You can't work out sums that big. That's what the Domnus says.'

Belisarius smiled at her. 'Yes, if you count the way the Romans always did. But I have Saracen acquaintances who have taught me some new tricks. I wish I had my abacus, though…'

He imagined a table of Saracen numerals, complete with that marvellous invention the zero, and worked through the division in his head. Seventy-six years and nine months. Very well, but what was this talk of 'midsummer', and 'nine of seven'? The words clearly meant the 'midsummer' of this Great Year marked out by the comet, and 'nine of seven' surely referred to nine times seven months, to be subtracted. Half of 921, less sixty-three, gave 397, rounded down, or thirty-three years and one month. That had to be reckoned from the beginning of the fifth great year; the fourth began in Anno Domini 684, and was 907 months long…

Boniface sat still, eyes closed, as Belisarius worked this through.

At last Belisarius had his result – and he was stunned. He turned to Aelfric. 'Tell me today's date, novice.'

Aelfric said, 'May the twenty-fourth.'

'The year! Tell me your Popish year, according to Bede's calendar.' '793, the Year of Our Lord,' said Aelfric. And her eyes widened when she saw Belisarius's shock. 'Is that the date of the fifth stanza?'

Belisarius could not deny it. In fact the prediction was even more specific: the dragon's claws would be unsheathed in the month of June, in this very year. Next month. Belisarius felt a faint whisper of fear, like a rumble of thunder from far across an ocean. He was a rational man, he liked to believe, in the tradition of Aristotle and others of his forebears. Though a Christian, he preferred to keep angels and demons in a separate corner of his mind, away from the business of real life. But now, in the body of this prophecy, that separateness was breaking down, and some impalpable threat was breaking through. Boniface's eyes were closed, as if he were sleeping, but a slight smile lingered on his lips. Belisarius had the feeling that Boniface the computistor had known all along exactly what the prophecy would reveal – and when this threat was due.

He straightened, trying to think. 'Our safest course is surely to assume this stanza is as true as the earlier verses, that this threat is looming. We must seek protection. Who can help?'

Macson shrugged. 'The King commands the fighting men. But how could we reach him?'

To Belisarius's surprise, Aelfric said, 'I know how.'

In the morning Belisarius and Macson rose early – though later than the monks – and impatiently waited out the latest service, after which they hoped to speak to Boniface again.

Macson complained of a growling stomach. 'These monks might fill up on the word of God, but my belly needs something more.' He jogged down to the village.

Hunger wasn't Macson's problem, Belisarius knew. In the end Belisarius had relented, and pointed out the obvious truth about Aelfric: that he was a she, that this boy monk was a girl. Suddenly Macson's helpless attraction to the novice made sense to him, but he was humiliated, and angry. Belisarius was careful not to mock him.

Macson returned with some heavy last-winter bread. Standing in the chill morning light amid the huddled buildings of the monastery, as birdsong competed with the high, thin chanting of the monks, they both chewed at the hard bread until it was soft enough to swallow.

When the monks filed out of the little wooden church to continue their day, Aelfric came to find the two of them. 'Dom Boniface is resting. He has a dispensation from the abbot not to join in the opus manuum in the middle of the day. He will speak with you then.'

Macson sneered at her. 'How good of him.'

Aelfric turned on him. 'Are you angry with me? Why?'

Belisarius said, 'I had to tell him you are female, which he couldn't work out for himself. You have muddled up his flinty British heart, Aelfric-or is that not your true name?'

'My father christened me Aelfflaed.'

Macson blushed. 'You are a liar,' he spat. 'Your whole life is a lie. Is that the way Christ and your Saint Benedict would have you live?'

Aelfric shot back, 'What's it to you?' In her anger she looked more feminine than at any time since Belisarius had met her, despite her grimy habit and the ugly tonsure cut into the crown of her hair. 'Perhaps the truth is you're disappointed I'm not a pretty boy after all.'

Belisarius said, 'I'm intrigued to find you here, Aelfric. Why is a girl hiding away in a monastery full of men?'

'There is nowhere else for me to learn. And my father thought I would be safe here.' She said that her father, called Bertgils, was a thegn of the current King of Northumbria, Aethelred. 'They call him Aethelred the Butcher,' Aelfric said gloomily. 'He is Northumbria's twelfth king in a century, of whom four have been murdered. Indeed Aethelred was once exiled, but won his throne back. And then to secure his position he put to death the infant sons of his rivals.'