The maps which Thomas Busshe had studied in the monastery all showed the Holy Land as the centre of the world. But he felt as if his extraordinary journey took him, not to the centre, but to the very edge of reality.

Even to cross the water to France was gruelling for a man who had sailed nothing more ambitious than a leather-stitched rowboat across the Thames. Then came the slog through the splintered kingdoms of France to embark again at Marseilles, and a sea journey ever further eastward across a hot, flat Mediterranean which he knew to be largely a Muslim lake. He followed his maps as he passed along the coastline owned by the East Romans, Christians who did not bow to the Pope, and whose ancient city of Constantinople was now, shamefully, in the hands of the crusaders who had sacked it. But as he ploughed ever further east there was only the huge mass of the Sultanate of Rum to the north, under the Turks who had taken Asia Minor from the East Romans, and the Fatimid Caliphate to the south, where the crescent of Muhammad fluttered over the cities of the Nile. Great sprawls on the map these were, like enormous Muslim hands ready to crush his frail ship like a fly.

In Palestine, true, there was the Outremer, his destination, the remnants of the Christian kingdoms planted bravely by the soldiers of the First Crusade. But these domains were shrunken now, split up and reduced to fragments by the dramatic conquests of Saladin half a century before. Even Jerusalem itself was only nominally in the hands of Christians. Seeing these little islands of the faithful on his maps served only to convince Thomas Busshe that despite the Pope’s ardent preaching, echoed in every pulpit in western Christendom, two centuries of crusading had resulted in little solid achievement, indeed perhaps the very opposite.

But that could all change.

Thomas, over fifty years old, was no warrior himself. But he had formulated for himself a mission that he believed might yet reverse the fortunes of Christendom, a mission inspired by a relic of the past that had come swimming fortuitously to him out of the dark, like the finger-bone of a saint emerging from the muck of a drained pond. A gift that, if he used his intellect well, might yet win the epochal war of civilisations for Christ.

And so he drove on, determined, clinging to the ship’s rail and trying not to vomit.

The climax of his extraordinary journey was at its very end. He landed at Jaffa, once more a Muslim city, and submitted himself to the ordeal of a trek across the dusty land to Jerusalem. And he met Joan and her son Saladin before the walls of the city itself.