The mosque was immense. Like its great sister in Cordoba, it was a complex of pillars and arches that extended off to infinity in every direction. Just days ago, this place would have been crowded with the Muslim faithful, Saladin supposed, perhaps still praying that Allah would save their city for them. Now there were only soldiers, all of them blazoned with the cross of Christ. In one corner he saw soldiers sleeping, leaning up against the wall. In another, more of them gambled with dice on the polished floor. And in the very heart of the mosque a fire had been built, right in the middle of the floor, and the soldiers were roasting a pig they had robbed from somewhere, no doubt brought here as a deliberate act of disrespect to the vanished Muslims. The smoke licked up and was blackening the fine plasterwork above.

Thomas had brought a few workers with him, off-duty soldiers standing idle with picks and shovels. ‘The difficulty is,’ he said, ‘where are we supposed to dig?’

‘I hadn’t thought this far ahead,’ Joan said. She strode about, looking around at the mosque. ‘I think I imagined it would be obvious. That those who buried the designs would leave some clue.’

‘None that is apparent,’ Thomas said. ‘We haven’t the time to dig the whole place up, and nor would the King spare us even if we did.’

‘Then what are we to do?’

‘Ask me.’ The woman walked towards them, out of the deeper shadows of the mosque. She wore a veil and a djellaba. She was obviously a Muslim, and had obviously been hiding. The woman removed her veil. She looked about fifty; her face was stern, determined - and familiar.

Michael made a deep growling noise. ‘Now that’s more like it. Old bones, but well worth jumping on, Saladin my friend, you mark my words—’

‘Shut up.’

Joan said, ‘I know you. You were in the meeting at the palace with the vizier’s staff.’

‘In the turayya, yes.’ She spoke a clear but accented English.

‘What do you want here?’

‘To meet you. You are here because of me.’ The woman smiled, but it was a stern, chilling expression. ‘I wrote to you, many years ago. I told you of the existence of the Codex of the Engines of God. I told you where the designs were buried. I hoped for cooperation. We are cousins.’

‘You are Subh of Cordoba.’

‘And you are Joan of the Outremer.’

The women faced each other. Saladin had rarely sensed such tension between two human beings, even in combat.

‘You should have fled with the others,’ Saladin said to Subh. ‘You must know you have put your life at stake by staying here.’

Joan introduced him. ‘This is my son, Saladin.’

‘Another relative.’ Subh smiled at Saladin, and turned back to Joan. ‘I would not leave without what is mine,’ she said. ‘No - ours.’