He reached the brow of the ridge, and overlooked the Danes' encampment.

The camp was set out like a letter 'D', with a half-circle of palisades and ditches pressed against a stretch of river bank. Arngrim could see tents of leather and sail-cloth, threads of smoke rising up from fires, horses corralled loosely. The ships had been hauled up on to the mud, their shallow draughts having enabled them to navigate even this far inland. The Danes always built their camps this way. They rode to battle on plundered horses and fought on foot, but they always preferred not to be too far away from their ships. Indeed it was said that you could wound a Dane more deeply by burning his ship than by striking down his son.

The warriors went about their business amid heaps of English treasure, extracted from the burned ruins of Alfred's hall. There were gangs of captives too, thegns, perhaps even ealdormen, great men of the kingdom of Wessex sitting in their own shit and tied together with lengths of rope like cattle. The Danes ignored the English save to prod them with their swords or piss on them, or they would pluck out a girl or a woman to be dragged into one of the tents.

Arngrim was close enough to hear scraps of the Danes' conversation. There was talk of taking the booty and captives back to Eoforwic – which the Danes called Jorvik, a captured town which was becoming a major market for the Danes. Meanwhile they were planning to use Cippanhamm as their base in Wessex for the rest of the winter. This riverside camp would serve as their river port, and a shelter for the ships. The assault on Cippanhamm was a classic example of the Vikings' way of working, Amgrim reflected, as every English thegn had learned from hard experience: surprise, attacks at night, the use of forests for cover, the ability to throw up rapid fortifications, their willingness to move into English settlements and use them as bases.

Amgrim did not see the Danes' leader, the petty king Guthrum. Nor did he spy Egil, the brutish leader of the war band.

'Hsst! Hsst!'

The call was loud enough to make Amgrim flinch. He looked back to the ragged copse at the bottom of this low ridge, where he had left Ibn Zuhr and Cynewulf. There was no sign of the Moor, but Cynewulf was standing in the open air, his habit streaked with dirt, filthy hair standing up around his tonsured scalp.

Furious, Arngrim waved him back. With one last glimpse down at the Danes he slithered on his belly down the ridge.

He met the others in the gloom of the forest. 'By Woden's eyes, what are you doing? Do you long for death, priest?'

Cynewulf, agitated, struggled for self-control. 'Oh, yes I do, you pagan oaf. I long to be free of the trials of this life, and to enter the peace of God which is forever beyond your hell-born understanding. But not today, not today. I must know. Is she there?'

'Aebbe? I did not see her. But she must be among the captives.' He described what he had seen of the camp.

'I don't understand,' Ibn Zuhr said, 'why they want all this plunder.'

Arngrim knew it was a sensible point. 'Among the Northmen the worth of a war leader is measured by the wealth he wins, and can give to those who follow him. We know this because long ago it was the same with us – and still is.' He raised an arm heavy with silver rings, most of them given him by Alfred.

'As for Aebbe, perhaps they have killed her already,' Cynewulf said gloomily.

'I doubt she is dead. Her youth and beauty will keep her alive.'

'The heathens will abuse her.'

'Perhaps. But they will not kill her.' Not unless, Amgrim told himself, she fights back too hard.

Ibn Zuhr seemed fascinated by the priest's distress. 'You are agitated by the plight of this Aebbe because of the information she holds. But what of the other captives? You are a priest of the Christians. I do not understand how a Christian can accept slavery – yet your society could not function without slaves.'

Cynewulf said, 'The Church tolerates slavery as a necessary evil, and an appropriate punishment for certain crimes. But the Church is concerned by the slave-taking by Danes, by heathens. And indeed by Moors. For the Church requires that all its devotees have the freedom to pursue their faith.'

'How enlightened,' Ibn Zuhr said dryly.

Arngrim valued Ibn Zuhr, but sometimes he pushed his luck. 'You ask barbed questions, Moor. Just remember you are a slave. Anyhow we're here to deal with the Danes, not debate philosophy.'

'How many in the camp?' Cynewulf asked.

'Hundreds. Not thousands.' In fact this was only a fraction of the original Danish force which had landed a dozen years ago; the rest had settled down to colonise the kingdoms they had shattered in the east and north.

'Hundreds.' Cynewulf shook his head. 'How is it that we fall like straw men before mere hundreds?'

'Few of us are warriors,' Arngrim said. 'The thegns are raised to fight. But the fyrd are farmers. And when the harvest is due they melt away anyhow. These Danes are blooded warriors. They do not fear a failed harvest for they simply steal food. What is worse, their war has become focused here, in Wessex, for the Danes have finished with the rest of England, save to farm it. It is only here that glory and booty may still be found, and so it is here that the hungriest warriors will come.'

Ibn Zuhr said, 'Every breath we take here we risk discovery, and an unpleasant fate. We must return to the King's camp with this intelligence.'

'But Aebbe-'

Arngrim grabbed the priest's arm. 'Perhaps we will be able to save her. But not today, cousin. The Danes are too strong.'

Ibn Zuhr nodded. 'We will go back the way we came. Follow me.' Moving silent as a cat, he crept through the forest, following a trail visible only to his own dark-adapted eyes, away from the Danish camp.

To the west of Cippanhamm there was a bank of forest, through which the King and his chastened party had retreated that dark night after the Twelve Days assault. Beyond this the ground rose to become boggy moorland where only a few stunted sheep browsed around heather-thatched hovels. During the retreat some of the thegns had begun to complain as the chill ice-crusted mud of the moorland weighed down their steps. But Arngrim and others, leading the grim flight, had known that the King would be as safe in this wilderness as anywhere else, for the Danes would be reluctant to move away from open water. Even the walled towns weren't safe; Escanceaster, for example, had been taken by the Danes the previous year.

As for the King himself, he seemed shocked to his core by the midwinter truce-breaking treachery of the Danes. With his priests and clerks fluttering around in their spoiled robes, Alfred had walked steadily into the dismal wilderness, looking neither left nor right, giving no orders, allowing himself to be led as passively as a child.

They had come at last to a place where the marshland was tidal, flooded daily by the Sabrina river, and in the sunlight open water shone everywhere, flat and calm and gummy with life.

'I know this place,' Arngrim had said. 'When I was a boy, we hunted here – my cousins and the athelings, Alfred and his older brothers. We called it the Isle of the Princes.' Aethelingaig. 'Alfred will remember it.'

'You have chosen well,' Cynewulf said.

Aethelingaig was inhabited: indeed people had lived here for a long time. You found your way from island to island along paths, causeways of logs pressed into the mud, ancient and endlessly renewed. The people lived in hovels on stilts, feeding off coots, moorhens, ducks, grebes, and gulls, and in the streams were weirs of brushwood, funnels in which eels and lampreys could be caught. Cynewulf had been told it was possible that these people might be British, clinging to land owned by deep chains of forefathers, land too worthless to have been taken from them by the new English dynasties.