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.

XIX

XIX

Ibrahim and Peter slipped out of Seville.

They came to a hole in the ground just beyond the city walls. It looked like the outlet of a broken sewer or drain. Peter said, ‘This is older than the Moorish city - Roman, we think, part of their sewage system. Of course the settlement here was a lot smaller then. The main Roman town, Italica, was some distance away. It’s a bit mucky down here—’

‘Just get on with it.’

The hole in the ground turned out to be a shaft, deeper than Ibrahim was tall, down which he had to drop. He found himself in a stone-clad tunnel, too low for him to stand up straight. He could see no further than a few paces. There was a smell of damp and rot, but nothing foetid; the sewer was long disused.

Peter used a flint to light a candle. His eyes were pits of shadow. ‘Are you all right? Not everybody is fond of the dark.’

Ibrahim took a deep breath. ‘I have no love of being buried alive. But it’s my mother I’m more frightened of.’

Peter laughed, and clapped him on the back. ‘Come. Let’s face our nightmares.’

It turned out to be only a short walk, though a clumsy and difficult one, through the low tunnel. Ibrahim stumbled over a broken Roman tile. Then the tunnel opened out, and Ibrahim found himself walking into a big boxy room. Steps cut into the earth led down to a floor some distance beneath him. The walls were stone-clad, the ceiling timbered, and lamps glimmered in alcoves.

And in this chamber, deep underground, machines brooded, dimly glimpsed. There was a great tube mounted on a carriage. An upright wheel turned, a treadmill, with a man inside it to work it. What looked like the skeletal form of a great bird’s wing gleamed and creaked. Scholars and artisans moved among these creations, murmuring quietly.

Ibrahim felt deeply uneasy, as if he had descended into a sorcerer’s pit.

Peter led him briskly forward. ‘This was some kind of water tank,’ he said in a murmur to match the subdued voices around them. ‘Always built big, those Romans, even when it came to their plumbing!’