Belisarius nodded. 'But this prophecy was not stolen from your ancestress. The wretched old man was the victim of this crime.'

'He was British, as was Sulpicia. Did she have no rights?'

It seemed to Belisarius a slight grudge to have been nursed over two centuries. But even slaves needed hope, it seemed.

Macson told him that the Menologium had been burnt, and its words had only survived at all by being committed to memory by the Northman and the German. After some generations a descendant of the German had been taken into the monastery at Lindisfarena with the Menologium in his head, and it was written down. And, with time, news of its preservation there had seeped back to the family of slaves who believed they had a right to it.

'So now you hope to reclaim it,' Belisarius said.

'There's every chance those chanting monks won't realise the value of what they have.' Macson glanced at Belisarius, calculating. 'And of course there may be profit to be made from it. For both of us.'

Such a curiosity, Belisarius conceded, would be of great value to the collectors of Constantinople, perhaps even in the emperor's court itself. The latter Romans, all good Christians, were just as fond of superstitions and oracles, omens and augers as their pagan ancestors.

Of course when they got their hands on this Menologium, if it existed at all, the manipulative Macson would think nothing of betraying Belisarius in order to keep any profit to himself. But Belisarius also had no doubt of his own ability to cope with such a situation when it arose.

That night Caradwc weakened. Macson came and said that the old man was asking for Belisarius. He longed to hear Belisarius talk of the holy sites he had visited.

So, in the light of a fire built in the ruins of Banna's headquarters building, Belisarius spoke of Bethlehem, where he had seen a grotto faced with marble, known to be the site of Jesus' birth. And he spoke of Jerusalem, where he had seen the hill of Golgotha, and the rock where the cross of Jesus had been raised, where now stood an immense silver cross and a bronze lamp-bearing wheel. And he spoke of a mighty church erected by the first Emperor Constantine, at the site where his mother Helena had discovered the True Cross.

'Helena, yes,' Caradwc whispered. 'The British always loved Helena…'

Those were the last words he spoke, and by the morning he was dead. With help from Belisarius his son buried him on the ridge that overlooked the river, his grave marked by a simple wooden cross.

Some days after her talk with Rhodri, as the whale-blubber candles burned smokily in the hall and the conversation rumbled contentedly, Gudrid approached her father with her suggestion that he should go back to Lindisfarena.

She wasn't surprised when he was sceptical.

'It might be fun to split open a few monkish heads,' Bjarni said. 'But it's not what we're going there for.'

'Then what?'

'Land. We need more land, Gudrid.'

Bjarni was a hefty man, with greying blond hair tied back from a high forehead, and a nose sharp as an axe blade. In his forty-five years he had done his share of fighting, but Gudrid knew that he had earned his muscles in building up his farms. He was not a natural raider, not bloodthirsty; he was embarking on this course of action for a wider purpose.

Bjarni was following in the footsteps of many of his elders. Like bees venturing from a hive, the ships of the Vikings were probing out of the overcrowded fjords. This was not directed by any king, for kings were weak in a land so divided by nature, but by the ambition of independent, wilful men. That probing was aimed not just at Britain and its islands but at the warmer lands further south, and even to the east, where huge rivers drained the heart of Asia, just as navigable by Viking ships as were the seas.

'The first raids are always vital. The German kingdoms in Britain are fragile, fractious, riven by internal strife. Everybody knows that. In the long term we should achieve great success against them. But the cheaper the success the better, as far as I'm concerned. And the element of surprise is everything.' He smiled at her. 'And that's why it would be a mistake to go chasing your dream of a family legend.'

'I won't deny that's what I want,' she said. 'But, Father, listen to me. There are other reasons to go to Lindisfarena. Those monks are rich. Richer than you'd imagine.'

He shook his head. 'That makes no sense. Nobody would store riches in such as vulnerable place as a coastal island.'

'You're thinking like a seafarer, not a Christian. Father, the monks came to Lindisfarena to convert their countrymen to their faith. They wanted a safe place to live. But the threat in their eyes came from the land, not the sea. And so they chose to live on a tidal island because it is hard to reach from the land. It doesn't even seem to have occurred to them that an attack might come from the sea. They will be quite defenceless.' She repeated what Rhodri had told her, about how pilgrims brought their money to give to the monastery. 'Believe me, those monks on Lindisfarena are rich!'

'Believe you, or a slave on the make?' He thought it over. 'All right, child. Just this one time we'll do as you say – if the others agree. One thing, though: are you sure this prophecy is worth all the trouble? Doesn't it speak of the Christ? Everybody knows the Christ is a powerful god. He has His adherents even here. Some of the men might fear tangling with His worshippers.'

She grinned. 'The Christ let Himself be nailed to a tree. I'd back Woden in a fight any time. Just give him a hammer!'

He grinned and clapped her on the shoulder. 'Gudrid, I've said it before and I'll say it again. Sometimes I wish you could be more like your sister Birgitta. But you have the mind of a son-'

'And the womb of one too,' she said bleakly.

He covered her hand with his. 'Have patience.'

'There's one more thing,' she said, pushing her luck. 'The raid on Lindisfarena.'

'Yes?'

'I'm coming too.' And she bolted from the hall before he had a chance to refuse.

Belisarius and Macson arrived at the north-east coast of Britain, opposite the island of Lindisfarena, early in the morning. As it happened the tide was high, and the island was cut off. There was no boat to carry them across, indeed no signs of human life on this sandy coast. So Macson led their horses to a patch of tough dune grass, and then came to sit with Belisarius in the shadow cast by their cart.

Belisarius wasn't sorry to be held up. It was going to be a warm day, and a humid one; the sea was like a pool of molten glass, barely stirring even as the tide tugged at it, and the Germans' holy island floated like a slab of pumice. It was pleasant to sit here, and to watch the birds wheeling over the sea, intent on their own tiny dramas of life and death.

And Belisarius was glad to see the sea again, to breathe in its sharp saltiness. He might even take a dip in the water at some point; the brine would wash out the sores and blisters he had picked up on the journey, and purify a skin that had gone too long without a proper cleanse, the only bath-houses on this benighted island being ruins where nobody had fired up the boilers for four hundred years.

As the morning wore on, the sea subsided. It was noon, the sun high, when at last they stirred themselves and made the crossing. The causeway's damp sand gave way under their querulous horses' hooves and clung to the cart's wheels. Macson walked alongside the horses, soothing them with soft words – German words for horses bought from a German – while Belisarius walked behind, steadying the cart.

The causeway was so low that at times the sea almost lapped at their feet, and half way across, suspended between the island and the mainland, Belisarius felt as if they were walking across the surface of the ocean itself. He remembered that these half-converted Germans were superstitious about border places, crossroads, liminal zones between one kind of landscape and another. Suspended on the hide of this ocean, Belisarius felt a flicker of their ancient fear of the world's edges.