A group of people, men, women and children, had gathered in a rough semicircle before the mosque's northern wall. Perhaps a hundred strong, they all seemed to be Christian. Many wore grubby crosses stitched to their shoulders, the papal symbol of the Reconquest. And they all seemed to be wielding stones, cobbles and lumps of concrete. Even the smallest children clutched pebbles in their tiny hands. It was a stoning, then. The Christians looked hungry for it to begin. There was no sign of any forces of order, of the Christian king's soldiers.

But Subh, without hesitation, marched straight into the middle of this mob. Subh's relatives hung back, but Ibrahim stayed with her, and Peter hurried after them.

At the centre of the crowd was a boy, dark-skinned, cowering against the wall. He stood awkwardly, dragging one wounded leg. His clothing was filthy and stiff with dark blood, and the left side of his face was swollen and battered. Two men stood near him, both stout and sleek, one expensively dressed, the other a Christian priest in his finery.

Subh stood proud before the cowering boy. 'You won't be harmed, Zawi. Stand straight, and stop that sniffling.' She glared around at the muttering crowd. The skin of her face shone with fine oils, and the slight breeze wrapped her loose white clothing around her so that her hips and breasts were prominent. In that moment of peril she looked magnificent to Peter, powerful, authoritative. Once again he felt a pang of helpless lust.

She called out clearly, "'He that is without sin among you, let him first cast a stone." Aren't those the words of Christ, recorded in the gospel of John? What, are you surprised that a Muslim knows the words of your holy books? I dare say I know your own creed better than most of you, and those tatty crosses sewn to your shoulders make no difference to that. Which of you fine Christians has condemned this snivelling boy?'

'I did, Subh.' It was the fat, finely dressed man who stood with the priest. His purple-dyed silk cloak must have been extraordinarily expensive.

'Alfonso,' Subh said with disgust. 'I might have known it was you. What do you accuse him of, muhtasib – mocking the size of your fat arse? If so you'll have to have half of Cordoba stoned.'

That actually won her a laugh.

Alfonso preened, plump fingers plucking at his leather belt. 'The crime is rather more serious than that, lady. This sand rat of a nephew of yours has fornicated with my granddaughter. My granddaughter, my Beatrice. Come here, child.' A girl, mousy, plain, stumbled forward from the crowd. 'Fornicated!' Alfonso thundered. 'What do you have to say to that?'

There was an angry murmur from the crowd.

Peter murmured to Ibrahim, 'In Toledo it's no stoning offence for a Muslim to sleep with a Christian.'

'In this town it is. And Alfonso is the muhtasib, who supervises the market. He is a man of influence in Cordoba.'

Subh was undaunted. 'And you have proof of this, do you, Alfonso the Fat? Oh, I'm prepared to believe that this wretched whelp of yours is no longer a virgin. But what else, beyond her word against his?'

'It was him,' Beatrice said, and she raised an unsteady finger to point at Zawi. 'He forced me!'

The crowd murmured again. But the priest looked down at his shoes, uncomfortable.

Subh, sharp, in control, noticed this. 'Forced you? Ah, but that isn't the story you told earlier, I would wager. Is it, child?'

'Yes – no – but it was Zawi, it was!'

Subh snorted, but Peter noticed she did not call on the boy to deny it for himself. She stalked about, regal, sneering at the stone-wielding crowd. 'And if so, what did you think of his scars?' Beatrice said nothing, and Subh went on, 'Come, child. If you lay together you must have noticed those.'

Beatrice glanced at her grandfather, uncertain.

Subh turned to the boy. 'Show them what I mean.'

Zawi's embarrassment apparently overcame his fear. 'But, aunt-'

'Show them. Drop your trousers.'

The boy complied, to reveal bare legs and a grimy sash around his waist. The crowd hooted, mocking his skinny legs and his shrivelled cock, and the boy was mortified. But Subh plucked aside the sash, and the crowd gasped at a mesh of scars on his belly.

'The result of a pious mule-whipping,' Subh said. 'A childhood gift from one of your sons, I'm told, Alfonso. Child, how could you not notice that?'

The girl, confused, stammered out, 'But I did sleep with him. All right, he didn't force me. But I did. It was in the orange grove behind the-'

Subh drowned her out. 'Your word against his! That's all we have. Who are you protecting, Beatrice? Who? Somebody known to your father – one of his business associates?' She spat that out with utter contempt. 'And for that will you take the blood of a boy on your hands? Will you go to meet your Maker with that unforgiven sin on your conscience?' She turned on the crowd. 'Will you? And you?'

As Zawi pulled up his trousers, Alfonso made one last try. He cried, 'You will not contradict me, woman! The facts of the case are clear! This girl has been violated. This girl, of a line tainted by no Moorish blood or Jewish, a Christian line that has survived since the days of the Gothic kings…'

But nobody was listening. One cobble was actually hurled, bouncing off the mosque wall harmlessly. But the mood for blood was gone, washed away by the sheer power of Subh's personality. Even the priest walked away.

Subh approached Alfonso. 'Gothic kings, eh? Well, I,' she said, 'am descended from Ahmed Ibn Tufayl, vizier to the emir of Seville, and that is no lie. I know the truth about you and your family, muhtasib. For centuries you called yourself al-Hafsun. My family worked with yours, in those days. You were muwallad. But when the Christian kings returned, you conveniently called yourselves Christian once more. Your blood is no more pure than your slut of a granddaughter.'

And she turned her back on a fuming Alfonso. 'One of you,' she called to her hapless relatives, 'take Zawi home and clean him up. And tell him that if he gets up to this kind of mischief again, especially with a Christian, and especially with a granddaughter of that slug Alfonso, I'll cut off his cock myself.' She rubbed her hands as if to clean them of dust. 'Well, that's that sorted out. Now, what's next?'She smiled brightly at Peter. 'What are you waiting for? Come with me.'

He dared do nothing else but follow.

In the patio of her home, Subh served Peter tea flavoured with the zest of an orange, and dried olives and apricots in thick cream.

It was May, and the garden was fresh, the leaves on the trees brilliant green, the roses flowering, the blossom on the pomegranates bright red. Somewhere a nightingale sang. This was a typically Moorish setting, Peter thought, an oasis-garden made by folk who cherished life where they found it.

But Ibrahim stalked about, restless. He seemed very angry that his mother had saved the life of his distant cousin. 'You lied shamelessly,' Ibrahim accused her. 'You knew very well that Zawi slept with that wretched girl. It was written all over him.'

Peter said, 'But the scars – the girl didn't recognise them.'

'He keeps the scars covered up with his sash,' Ibrahim snapped. 'Even while making love. Wouldn't you?'

'Oh, of course I knew he slept with the whelp,' Subh said. 'Why do you think I didn't question him? For fear he would blurt out the truth, or still worse profess some undying passion for the spread-legged little she-goat, and get himself put down.'

'And you made an unnecessary enemy of Alfonso in the process.'

'But he is already my enemy. You see, my son, I believe that to lie is wrong, but to allow a foolish boy to be stoned for a bit of careless lust is more wrong still.'