When he had turned up at the vizier's office in the emir's palace, offering to help in any way he could, Ibrahim had found plenty to do. He found he was capable, unexpectedly good at finding solutions to novel problems, and implementing them. Perhaps he had inherited something of his formidable mother's qualities. He rose rapidly in authority, and in the scale of the problems he was given to solve.

Something about the work satisfied a deep spiritual need inside him. He still adhered to the teachings of the Almohads, named for Almuwahhidum, the Oneness of God. In his patient work he felt he was healing damaged lives; it was a work that served God's unity better than any amount of killing, he thought.

'But,' Peter said, 'how long can this continue, Ibrahim? This is a city under stress. King Fernando doesn't even need to attack; the steady pressure he is applying is slowly winning the battle for him. All you are doing here is managing the city's decline.'

'Not necessarily.'

'Of course necessarily; that's the truth. But if your mother's weapons designs were to pay off – if even one of them came to fruition – then the whole situation could be transformed.'

Ibrahim snorted. 'If a miracle happens? If Saladin came back to life and led us to victory?'

'We don't need a miracle. Your mother's engines are taking shape, Ibrahim, manifested in steel and leather and wood, only a short walk from this very room. Don't you think it's your duty to come and see what we have – your duty as an officer of the emirate, and a son?'

Ibrahim stared at him. In the far distance he heard angry shouts, the crash of smashing glass, harsh military orders: the sounds of a disintegrating civilisation. He felt his determination wavering.

XVIII

Thomas Busshe sought out Saladin in northern England, where he had gone to ground three years after he had arrived in Britain. Saladin soon learned that Thomas was coming to tell him that his mother needed him, and he must come back to London.

The monk stayed a single night in the manse itself. It was the home of Saladin's employer, a petty knight called Percival. The next morning, very early, Saladin found Thomas walking in the village. Thomas was showing his age, Saladin thought. His eyes were shadowed, and he looked stiff after his hours on the mead bench with Percival. But here he was, up and about. 'It's the relentless rhythm of a monk's life,' he said. 'You can't get it out of your blood.'

They walked around the village. It was a mean place, a street of long sod-built huts surrounded by a sprawl of plough land. The manse was a small robust house of decently cut stone, which Saladin told Thomas was made of stones robbed from Hadrian's Wall. Thomas seemed to think that was an enchanting idea, the labours of long-dead centurions transformed into the houses of the living.

They came across a group of men setting off for the day's work. They nodded to Saladin, not warmly, but civilly enough. They were skinny men with sallow faces. Hunched against the slight chill of the dewy air, some limping slightly, they were wood-cutters, and they bore adzes and axes and saws. They wore grimy, colourless clothes, breeches, hoses, shirts, kirtles – Saladin knew that these were the only clothes that most of them owned. As they plodded along they sang a song so filthy that Saladin hoped their strong Northumbrian accents, heavily laced with Danish words, would make it incomprehensible to Thomas.

'Many of them are blond,' Thomas said, surprised.

'That's the Viking blood in them. A lot of it about in this area.'

'Do you get on with them?'

Saladin grinned. 'They call me the Saracen, or the Moor, or Muhammad. Ironic, that. But they've never seen anybody like me before.' He grunted. 'In fact most of them have never seen anybody from beyond that hill over there.'

'And all our cathedrals and all our palaces and all our wars rest on the foundation of the toil of the country people, like these.'

'Makes you think,' Saladin said.

'It does indeed. And you found work here.'

'I accompany Percival's bailiff when there's trouble with the tithes,' Saladin said. 'I'm a hired muscle. Every so often we ride to a borough, to Newcastle or Morpeth, so the lord can pay his own tithes, and for the market. I go along to put off the robbers. I enjoy the market. I can buy stuff that reminds me of home, a little. Raisins, cinnamon, figs.'

'The fruit of sunnier lands. And are you happy, Saladin?'

Saladin shrugged. 'Ask those wood-cutters if they're happy. You've got what you've got and you have to put up with it. That or starve. It wasn't easy for me when we first came here to England – how long ago?'

'Three years already.'

'I needed the work. My mother and I had no money left. But I had no close family, nowhere to go.'

'And a face that didn't fit.'

'Yes. I'm grateful to you for finding me that first bit of employment with Umfraville.' A lord with extensive holdings here in the north country, who had made himself rich from a king's commission to protect the main droving routes to the north from the marauding Scots. The Umfravilles' castle at Harbottle on the Coquet was grand. But Saladin didn't have the stomach for the subdued, spiteful, slow-burning sort of war that consumed this border country – subdued but unending, for the nobles who waged it on both sides of the border grew rich from it. He had been glad to move to the pettier house of Percival.

Happy? Happiness was irrelevant in this life, he thought. Content? Yes, perhaps that was the word. Percival was a man of no brain, it seemed to Saladin, and too drunken to formulate any serious ambition. He was happy just to take his villagers' tithe and piss it away into the soak-holes behind his hall. But Saladin had no desire to risk his life supporting the petty ambitions of a more restless lord.

'This will suit me for now,' Saladin said. 'Until something better shows up.' He eyed Thomas. 'But my mother isn't so content, is she?'

'I'm afraid not.'

'I send her my money, you know. Just about all of it, keeping only a little for myself to buy a bit of pepper in Newcastle. I have few needs here; I eat with the lord, sleep in his house, ride his horses. What use is money?'

'She'd be lost without your contribution.'

'You wouldn't let her starve,' Saladin said.

'Well, true. We remember our benefactors. But she's a proud woman, Saladin. She doesn't want charity from a "gaggle of monks", as she calls us.' Thomas sighed. 'But she has ambition enough for a hundred English lords.'

'Jerusalem remains in Saracen hands.'

'So it does. But things have changed, Saladin. You and your mother arrived here without wealth, but with one treasure.'

Saladin said reluctantly, 'Robert's cipher.'

'Yes. Perhaps you remember I found a scholar to study it – another Franciscan, a man called Roger Bacon. Remarkable chap. It's taken him some time-'

'Let me guess. He's worked it out.'

'So he claims. We'll have to judge his results.'

'We?'

'Your mother wants you with her, Saladin. In London, when the truth of the Incendium Dei code is revealed.'

Saladin said, 'I always hated that old nonsense about prophecies and codes, Thomas. Maybe it made our family rich in the past. But it never helped us in the Outremer, or since we have come to England. And I never thought it was real.' He waved a hand. 'Not compared to this. Land, toil, iron, blood, war – that's the real stuff of life. But my mother wants me with her in case this cracked code reveals secrets that will revive our fortune, and fulfil her life.'

'Yes. And I want you with her,' Thomas said severely, 'in the much more likely case that it does not.'

Mulling over Thomas's words, Saladin led him back to the manse.