The Sebastokrator Isaak was the first to find his voice. ‘The barbarians,’ he hissed. ‘They must have planned this, to murder you in your own hall and seize the crown as it slipped from your head. Let us kill them now, and then fall upon their kinsmen in their camp.’

I saw Krysaphios nodding behind him, but Alexios raised a weary hand to still them. There was a gash in his sleeve where Aelric had landed his final, glancing blow. ‘Do not touch the ambassadors,’ he commanded, imposing authority on his shaken voice. ‘Why would they attempt such a crime when they were my hostages? They must have known their lives would be forfeit if anything happened to me while they were here.’ He paused. ‘Unless, of course, there was another candidate ready to take the diadem and command the mob to save them.’

His sharp eyes glanced at each of us in turn, fixing – so I thought – a second longer on Isaak than any other.

‘We will seek out all who have a claim to the throne and establish their whereabouts,’ said Krysaphios. ‘And we should deploy the guard in the streets, lest in haste someone has already started to move against you.’

‘Can we rely on the guard?’ asked Alexios. ‘If one of my longest-serving Varangians will betray me, whom then can I trust?’

Sigurd winced; he seemed on the edge of tears. ‘The Varangians will defend you to the death, Lord. But if you do not trust us, then take our arms and make us your slaves.’ Dropping to his knee, he held his axe by its blood-swathed blade, and offered it to the Emperor.

‘Take it, Lord.’ Krysaphios kicked angrily at Aelric’s headless corpse. ‘If you do not know why a Varangian should have done this terrible thing, you cannot tell us why another may not try again. Was he a traitor all this time, waiting for his moment to strike? If so, why now? Was it a moment of madness? Or did he indeed act for a wider cause among his legion?’

‘On balance,’ I observed, ‘it would have been useful if Sigurd had not been so quick to dismember him.’ I looked at the staring, lifeless eyes and shuddered. This was a man who had ridden at my side and eaten in my home: it was not easy to see him now. ‘It would have been worth everything to know his motives.’

Sigurd, still on his knee, growled. ‘You can wrestle a snake to the ground, Demetrios, but to be sure it will not bite you must behead it. My duty is to keep the Emperor from harm – yours is to find those who would harm him before they enter his presence. Which of us has failed today?’

‘My task would be easier if you did not help the monk by destroying every link with him.’

Sigurd looked as though he might like to use his axe again, but Isaak spoke to me first. ‘What of the monk? There is a greater power at work when the Emperor is almost murdered in his own palace, and you think only of spies and foot soldiers. Forget the monk, if he even exists, and instead seek out his masters.’

I was about to retort unwisely, for in all this argument it seemed my own role in bringing down the assassin was forgotten, but I was forestalled by an urgent rapping on the door, and the sound of voices in the passage beyond. We turned, and Sigurd raised his axe, though Alexios stayed unmoved.

‘Who disturbs the Emperor?’ Krysaphios’ fear wrought anger in his voice.

‘Your pardon, Lord, but it is urgent,’ said a voice behind the door. ‘The watchmen on the walls report smoke rising from the outlying villages. The barbarian army has begun to riot, claiming that we hold their embassy hostage and demanding their release.’

Isaak exploded. ‘You see brother – already they are moving. Their haste betrays them. Let us chain the hostages and ride out to face our enemies.’

Alexios ignored him. ‘Captain,’ he said, beckoning Sigurd. ‘I will not disband your legion. Long service has proven their value; I would be an ingrate and a fool to squander it because of a single man’s treachery.’ More immediately, I thought, he could ill afford to lose good troops with the barbarians so near. ‘Fetch your company and escort the envoys to the gates. Explain that I will await their answer in the coming days.’ He pulled his lorum straight, wiping a drop of blood from one of its gems. ‘If so much as a single strand of their hair is harmed, either by your men or by the mob in the city, you will answer for it personally, Captain. Is that clear?’

Sigurd nodded, bowed, and backed from the room, while Isaak glowered in the corner.

‘Now,’ continued the Emperor. ‘Find me the captain of the Patzinaks. I have forgiven the Varangians the traitor they unknowingly harboured, but I cannot keep them in the palace if even a single man is suspected. I will need men about me I can trust, for it will be another day at least before we know if the danger is passed.’

‘The danger will never pass so long as the barbarians live outside our walls,’ muttered Isaak.

‘Unless the danger is already within.’ Krysaphios turned to me. ‘Demetrios, you remember the list I showed you once?’

It was almost two months since I had seen it, but I remembered enough of its eminent names to manage a convincing nod.

‘Then take a company of Patzinaks and find where those men are as quickly as you can. Any who have taken sudden trips to their country estates, or who have hoards of arms cached in their cellars, or who have tried to slip through the gates in disguise, report back to me. I will be at the new palace with the Emperor.’

I nodded my obedience. ‘And what of Aelric? Someone must know, or guess, the motive for his treachery. Some of his comrades? His family, perhaps?’

Krysaphios shrugged impatiently. ‘Perhaps. You can ask Sigurd when he returns. Though do not seek him in the palace – by nightfall all the Varangians will be at their barracks by the Adrianople gate.’

I made my obeisance and left, stepping over Aelric’s riven head as I did so. The blood had matted through his greying hair, and the jaw was slack, but the eyes remained as firm as ever, fixed where Sigurd’s vengeful blade had swung.

And hour after hour, as I asked the expected questions and heard the expected answers, I struggled with the motive of the crime. Aelric could not have hoped to gain from his treachery, for even had he felled the Emperor he would have died the next instant. Unless madness or an evil spirit had taken hold of him, someone must have driven him to attempt the murder with a threat greater than certain death. What could that be – and who? It might have been the monk, but whose ends did he serve? Was it as Isaak suggested, that the barbarian envoys had hoped to use the confusion to their advantage? That was madness, for they would have been slaughtered to a man. Or was it the barbarian captains, away in their camp, hoping that the Emperor’s death would give them an excuse and an opportunity to take the city? That was almost too fanciful to credit. Or were the barbarians simply a distraction, an irrelevance in a political contest fought among our own nobles?

I found no answers, but when my task was done I took the notes to Krysaphios at the new palace. Such was my exhaustion, my shock, that I did not argue when the guard announced that the eunuch was unavailable: I called for a secretary, sealed the book with wax, and left it with him to relay to his master. Then, as it was not far, I walked along the hilltop in the shadow of the walls to the Varangian barracks.

‘Is Sigurd the captain here?’ I asked.

‘On the ramparts,’ answered the sentry.

‘Can I speak with him?’

‘You can,’ he said dubiously, ‘though you might regret it. He’s in an evil mood.’

‘I’ll risk it.’

I crossed the parade ground and climbed the broad stair up to the wall, watching my breath cloud the bitter air. The sky was clear, a swathe of purple far above me, and the first stars were beginning to prick through. They reminded me of the Emperor’s opulence, the glittering gems set in the imperial fabric, and I wondered who would have been wearing those robes tonight if I had been a second slower. The Sebastokrator Isaak? The Emperor’s first son, barely eight years old? One of the eminences whose servants I had interviewed that afternoon? Or a barbarian from the west, sitting awkwardly on the throne watching the abomination of an empire?

I found Sigurd alone, leaning on the deep embrasure between two battlements and staring out at the sparks across the water where the barbarian campfires burned. He grunted when I greeted him, but did not turn to face me.

‘It seems so tranquil,’ I mused, pulling my cloak tight about me. ‘Truly, night smoothes the fractures of the world.’

‘But night dawns, and it will be a long time before the fragments of this day are forged back together.’ Sigurd tipped a clay flagon to his lips, and I heard the gulping of liquid tumbling from its throat to his. ‘Wine?’

‘Thank you.’ It was coarse stuff, but a welcome tonic against the cold.

‘Though you’ve no cares. You saved the Emperor’s life. You can expect a house and a pension for such service. I let a traitor destroy the honour of the Varangians, and come within an inch of razing the empire.’

‘So who guards the Emperor now, if the Varangians are expelled from the palaces?’ My fevered mind wondered whether Aelric’s deed had merely been a gambit to discredit his legion, to leave the Emperor vulnerable.

‘Patzinaks.’ Sigurd’s voice implied they might as well be lepers. ‘Round-faced barbarians from the east: an ugly race, with ugly women and uglier habits.’

‘Reliable?’

‘As rocks. Once the Emperor defeated them in battle; now they worship him as a god, and serve him as zealots. I once saw a Patzinak stand for four days and nights in driving snow because no order came to relieve him.’

There was a silence as we swapped the wine again. I leaned against the massive parapet, and felt the cold of the stone on my cheek.

‘I know your wounds are sore,’ I began again, ‘but there are questions which need swift answers before the trail fades. Did Aelric have any particular comrades in the guard? Or a family?’

‘He was in a company of men who were all like brothers. But do not seek answers from Sweyn or Stigand or any of the others: they were as ignorant as me. Otherwise Aelric would never have crossed the palace threshold, except in chains. He had a family, though – a wife, Freya, and a son.’

‘Do they live in the barracks?’

‘None of the women do. The wife keeps a house in Petrion, not far from here. The son left home years ago – he probably has grandchildren by now. Remember, Aelric was already a warrior when most of us were still sucking on our mothers.’

‘Did you know him then? Back in Thule?’

‘England,’ Sigurd corrected me automatically. ‘No – our paths here were separate, and it was years later, when I was a grown man, that we met.’

‘And his wife – did he meet her here, or was she also from England?’

‘English. She fled with him after the Bastard conquered us.’

‘I think I had best see her. Will she already have been told Aelric’s fate?’

‘I doubt anyone has thought of her until you, Demetrios. You may have to relate the news yourself.’

‘Will you come?’

Sigurd drained the last of the wine and tossed the bottle over the parapet. I heard it shatter on the stones below.

‘I cannot leave this place.’ He kicked at the battlement before him. ‘We are not allowed any closer to the palace than these walls.’

On balance, I decided, it would probably be better to arrive at the widow’s house without her husband’s murderer.

‘I have come from the palace. It concerns your husband.’ My words haunted the empty street.

Three times I heard the sounds of bolts being drawn. Then the door cracked open.

‘You are not of the Varangians. Have I seen you before?’

All was darkness beyond the door, but the voice bespoke someone old, a woman pinched by a weary life.

‘I am a stranger,’ I admitted, ‘but I knew your husband. He . . .’

‘You knew my husband?’ The door edged open a fraction further. ‘Why is it that you knew my husband? Where is he now?’

‘He is dead.’

I had not meant to say it so baldly, but it was out now and I could curse my carelessness later. I heard a wail arise in the room within, the sound of someone stumbling about, and I pushed in through the door before she could slam it on me. Small fists flailed against my chest, and I raised my arms in defence, though there was little force in her bony blows. The darkness hindered me, but eventually I managed to catch hold of her wrists and hold them away, until the screams of defiance broke down into a forlorn sobbing.

As gently as I could, I steered her backwards, away from the door. She was weeping, calling her dead husband’s name and many other things in a tongue I could not understand.

‘Do you have a candle?’ I asked as she took a choking breath. ‘It would help if I could see you.’

Tentatively, I relaxed my grip a little, testing whether she still aimed to attack me. There was no sudden movement, nor any increase in her sobbing, and so I let her loose.

She moved away. For a second I feared she might be fetching a blade, might assault me in the darkness, but then I saw a shower of sparks in a corner and the flare of a wick. The candle was burned low, crusted with shrivelled knobs of wax, but it gave enough light that I could at last see Aelric’s poor widow.

She was old, at least as old as he, and the deeply-shadowed furrows of her face added still more years. Her ragged hair was grey and untied, hanging in frayed bunches, and her skin shone with tears. Dressed only in a woollen shift, she fell back onto a stool and gestured me to take a bench. I reached out a hand to stroke her arm, but she recoiled in loathing and huddled herself away.

‘Did Sigurd kill him?’ she asked.

The question startled me, so much that I could do little but flounder for a minute before admitting: ‘Yes.’ And then, struggling to impose myself: ‘Why should you think so?’

‘My husband always feared it, that Sigurd would find his secret and murder him in a fit of rage. Every day in the last ten years, since Sigurd joined the Varangians, Aelric feared him.’

She scratched her scalp through her thin hair, and shivered as though a draught had blown over her.

‘Why did Aelric fear him?’ I asked. ‘What secret could he have kept that would have inflamed Sigurd so? Was his purpose with the Emperor always . . . ?’

‘The Emperor?’ Aelric’s wife – Freya, I remembered was her name – gave a bitter laugh. ‘What did Aelric care for the Emperor? Or Sigurd, for that matter?’

‘Sigurd loves the Emperor like a father.’

‘Love?’ Freya spat on the floor. ‘None of you act from love – but from hate. Sigurd does not love the Emperor; he hates the Normans, and with a merciless passion. Why else would he not forgive Aelric, who brought him into the Varangians and was like an older brother to him?’

‘But what had Aelric done?’ I was bewildered; it was like trying to knead oil, reasoning with this woman.

She ignored me. ‘He knew it was returning. So did I. Ever since Asgard appeared at our door three weeks ago it haunted him. Aelric, who served the Emperor long after most of his companions would have hung up their armour and taken a farm in the country. Will Sigurd still be standing his watch when he is as old as Aelric? Never.’

‘Who was this Asgard? Another Varangian?’

‘He came three weeks ago, and Aelric changed. His smile vanished, and his shoulders sagged; he would hardly eat. At first he did not speak of it, but I knew, for what else could Asgard have to talk to him about? Then Asgard called again and took him away: to meet his friends, he said. And now he is dead, the most loyal man who ever carried an axe. My husband.’

I leaned closer, trying to find some thread to guide me through the fog of her babble. ‘And what was this secret of Aelric’s that Asgard wanted to talk of?’

Freya straightened, defiance kindling within her. ‘Why should I tell his secrets to a stranger, the crow who croaks his death?’

‘Because all our safety depends on it – and yours especially. If you do not tell me others will come, and they will not be as gentle as I. Before he died, Aelric betrayed the Emperor and the Varangians, and that will not be forgiven lightly.’ I had not wanted to touch on Aelric’s treachery, and it had been a sound instinct, for Freya plunged her face into her hands at the sound of it.

‘My husband was an honest man who served his masters faithfully,’ she sobbed. ‘If they were devious, or evil, or made him defy his nature, then God will judge them, not him. And you call yourself gentle – you, cursing his name to me while my tears are warm, before he is even laid in the ground. Get out of my house, and allow me my grief without poisoning it.’

‘I cannot. I must know . . .’

‘Out! Out!’

She would not be consoled, certainly not by me, and until then I would get no sense from her. I left her to her tears, and hurried back to the walls. It seemed the night had lasted an eternity, but Sigurd was still there, pacing the ramparts and scanning the dark horizon with vacant eyes. Neither of us offered a greeting.

‘Do you know a man named Asgard?’ I asked. ‘Maybe a Varangian, or someone from the palace.’

Sigurd’s scowl, if it were possible, deepened. ‘I know Asgard,’ he grunted. ‘He was a Varangian, until a few years ago. I expelled him myself for stealing from us, thieving in the barracks.’

‘Did he know Aelric?’

‘They escaped England at the same time, and arrived in the city together: Asgard and Aelric, their wives, a few others. Most are dead now.’

‘But not Asgard?’

Sigurd raised his hands in ignorance. ‘I could not care. I heard that he kept a stall in the fur market, selling mangy pelts and skins that the Rus traders could not persuade any others to take. Maybe he’s still there, maybe not. He was a worm, and we were well rid of him.’

‘He did not keep in contact with any of your men?’

‘They would have spurned him. Stealing from your messmates is like stealing from the church – except that we have no obligation to forgive. Why all this curiosity? Do you want a cheap shawl for your daughter?’

‘He visited Aelric several times in recent weeks. Freya blamed him for a change in Aelric’s mood, and I think he may have carried messages for the monk.’

Sigurd snorted. ‘The monk? The monk is a phantom, Demetrios, an apparition. The sort of man you blame when there are no other excuses.’ He paused, pondering this. ‘Asgard, on the other hand – he’s real enough. Seek him in the market.’