‘Yes. And here is the strangest part of the story. Just as in al-Andalus, Christianity will be tolerated - even a thousand years after Abd al-Rahman. But the bitter monks of Lindisfarne and elsewhere will be pinpricks of Christianity in a Muslim map. Christ will live on through them, for al-Hafredi quotes Matthew, chapter eighteen: “For where two or three are gathered together in my name, there I am in the midst of them.” But Islam will be everywhere else. The situation will be intolerable, the whole world lost - and in the end, al-Hafredi feared, Christianity would be extinguished altogether. Something must be done.

‘So the devious monks will steal one of the Moors’ own marvellous engines, and hatch a plot to use against its inventors. Don’t ask me how it is done - I barely understand the what, let alone the how. But they will find a way to hurl one man across history, just as my crossbow will hurl a bolt across the sky, just as your Witness sent her words across the firmament to Eadgyth - they will hurl him, naked and alone, into another time and place.’

Orm saw it. ‘They sent al-Hafredi from Lindisfarne, in this future century, to Poitiers, in the deep past.’

‘That is what al-Hafredi tells us happened to him,’ Sihtric said firmly. ‘And, following the mission that had been devised for him, he made his way to Odo, and turned that weak man’s mind around.’

Orm tried to take all this in. ‘If that was his mission, he succeeded. This other Europe is now extinguished altogether. The mosque of Paris, the great library in London—’

‘They never existed - and never will.’

Orm thought of the beauties he had seen here in al-Andalus, and he remembered the Normans’ harrying of the English north. ‘Do you think this world, our world, is a better one, Sihtric?’

Sihtric sniffed. ‘That other wasn’t a Christian world; it deserved to vanish.’

Orm studied the vellum again, and stroked it gingerly with a fingertip. ‘What is this stuff - goat, lamb? Why didn’t your long-dead scribe use a better quality bit of leather? These wounds are odd. This one looks like an arrow puncture. Was this animal hunted down?’

Sihtric eyed him. ‘Can’t you guess what this is, Viking? A pity; I thought you were showing imagination for once. Think about it. Al-Hafredi brought back an account of his own lost future in written form; perhaps he feared that his crossbow-shot across time would leave him dead, but that his message might do some good even so . . . And yet he travelled naked.’

Orm saw it. He drew his hand back. ‘He bore his message on his body.’