The vizier stood tall, his mouth drawn wide, the muscles in his neck spasming. So deep was his rage, so toxic the drink swilling in his body, that for a heartbeat he seemed unable to act, even to speak. The guards fingered their scimitars uneasily.

But Sihtric was not frozen. He turned to Moraima. 'Goodbye, my lovely girl, my darling. All my life I have chased such grand ambitions. And yet in the end, if all I leave behind is you, perhaps it's enough.'

Moraima asked, bewildered, 'Father? What do you mean?'

'I will not see Christendom threatened – not through my own foolishness and arrogance. You say that everything I've achieved is gathered in this room, vizier. Then it must end, here in this room.'

And Sihtric jumped up at the wall, grabbed an oil lamp, and hurled himself on the heap of manuscripts in the corner of the room. The lamp broke under him, and fire blossomed around him, licking eagerly over the stacked scrolls and books, and Sihtric's robe. Ibn Tufayl let out a bellow of drunken despair, and threw himself at the fire. Orm grabbed him, whether to hold him back or to wrestle him Robert couldn't tell. But in a moment the two of them had toppled into the blaze on top of the squirming priest.

It had only taken a heartbeat. The room filled with smoke. The screams of the three men were high and terrible. Moraima lunged forward, but Robert held her.

The guards ran into the room. Some of them tried to drag the bodies from the pyre, only to be burned themselves and driven back, and others, with more presence of mind, ripped hangings off the walls and hurled them on the fire. The smoke was dense now, and, his lungs seared, Robert began to cough.

'Robert. Hsst. Robert!' The voice carried to Robert through the roaring of the blaze, the panicky shouts of the Berber guards. Ibn Hafsun the muwallad stood in an archway, only dimly visible through the billowing smoke. 'Let's get out of here. Bring the girl. Move, while you have a chance. Come on!'

Dragging an inert Moraima, Robert hurried that way. The guards were too occupied with the blaze, and the smoke too thick, for them to be seen and stopped.

But as he reached the arch the little serving girl stopped him. 'Please,' she said in heavily accented Latin. 'Please!'

Robert, anxious, tried to get past. But, her face soot-streaked, a burn livid on her right arm, she held up a scorched scroll, wrapped in an animal skin. She pointed at the blaze. 'Priest, priest!'

Robert grabbed the scroll and ran out, dragging Moraima, following Ibn Hafsun.

Ibn Hafsun, Robert and Moraima slipped out of Cordoba. They rode down the Guadalquivir towards Seville, a bigger city where, Ibn Hafsun said, it would be easier for them to lose themselves, while the fuss died down.

Ibn Hafsun was vague about why he had saved them. 'I brought you across Spain, Robert, for a fee. I suppose I've always felt responsible for you. I didn't mean to lead you into such peril – and nor did I mean to play a part in the deaths of Sihtric and Orm.'

'It wasn't your fault,' Robert said.

'Perhaps not. But I'm a muwallad, Robert. A Muslim, but with a healthy dose of ancestral Christian guilt left in my bloodstream.'

As they journeyed along the course of the great river, Robert was distracted by the changing landscape. Al-Andalus might have declined since the end of the great days of the caliphate and the fitnah, but there was prosperity here. Huge ships sailed the length of the river, laden with goods. Near Seville the land was heavily farmed. Plantations of sugar cane sprawled amid ranches and stud farms where tremendous herds of horses flowed.

As they travelled, each morning Moraima was ill.

The two of them spoke little. Moraima was immersed in her loss and the churning of the new life inside her body. And Robert, brooding on Orm's death, his head full of the stern strength of his new faith, found he had nothing to say to her. In the evenings, in taverns or camped out in the open, Ibn Hafsun watched them sitting apart in silence, and sighed, and rolled over in his blanket to sleep.

Seville itself was bustling, prosperous under the Abbadids, the ruling family. Ibn Hafsun said that the river was navigable from the sea to this point, making Seville a natural port. There was a fortress here, built centuries ago by Cordoban governors. Now it was being extended by the Abbadids into a palace to be called al-Murawak – 'the Blessed'. If Cordoba's great days were over, it appeared that Seville's still lay ahead.

They came to a place a little way to the north and west of the fortress walls, where a small mosque stood. Ibn Hafsun said, 'You say Sihtric spoke of a great mosque to be built in Seville. If it is to be built anywhere, I judge it will be just here, for the position, close to the palace, is ideal.' He glanced around at the somewhat shabby mosque, the tangled streets. 'It's unprepossessing now. But it would be fascinating to come back in a century or two, and see what time has made of this place.'

Robert glanced at Moraima. 'We should make plans,' he said. 'Ibn Hafsun has brought us this far. Now it's up to us.'

'I have family in the city, on my mother's side,' Moraima said. 'The aunt who would have raised me. We could stay with her. She wouldn't betray us. She never liked grandfather much.'

'Or-'

'Yes?'

'Or we could take a ship for England.'

They eyed each other. Moraima's face was full of her loss, of her father and grandfather. A loss that, perhaps, she blamed him for, in some indirect way.

And Robert saw her from a distance, as if through a window of stained glass.

He was fourteen years old, and was battered by contradictory experiences. In a few days he had lost his father, but he had found a core of true Christian faith. When he had first travelled across al-Andalus his soul had opened up to its light and its beauty. But now he imagined a day when this country would be studded with solid churches and cathedrals, and the folk working these rich fields would all be good Christians. He imagined that future, and dreamed inchoately of playing a part in bringing it about.

And in the world as he saw it now, with a new clear vision and orderly head, he found little room for a Muslim girl and her half-Muslim baby.

She saw this in his face. She turned away.

He dug the scroll out of his pack. Badly scorched, it was crumbling. 'We must decide what to do with this.'

Ibn Hafsun glanced at it, interested. 'What is it?'

'It was saved from the fire. I think Sihtric thrust it out to a serving girl, who passed it to me… I have told you of his visions, the engines. These are the original sketches, I think, taken from the English monk.'

Ibn Hafsun touched the battered scroll. 'The Codex! And nearly complete. Marvellous, marvellous. And it is wrapped in this bit of skin – is it tattooed somehow?'

Robert took the bit of skin, fingering it curiously. It was damaged by an arrow wound.

'But they are useless,' Moraima said. 'These designs. My father always said they needed the Incendium Dei, which his alchemists could never puzzle out.'

'Useless?' Ibn Hafsun laughed coldly. 'I wouldn't have said so. How many have already died as a result of this Codex?'

'It is useless,' Robert said. 'And my mother's vision even more so.' In the end, as far as he knew, Sihtric and Orm had never even discussed properly the 'Testament' that had brought Orm all this way in the first place. It had all been folly – a dreadful waste of life.

'Well,' Ibn Hafsun said, 'if you two aren't to stay together, what will you do with the Codex?'

'It's a Christian relic,' Robert said. 'I won't see it in Muslim hands. Perhaps we should destroy it.'

'It belonged to my father,' Moraima snapped. 'I won't see it destroyed.'