Based on an extraordinary but real story, this begins with the capture of a young Highland soldier, a former apprentice gunsmith from Edinburgh, in the Egyptian war of 1807, and describes the long and complex path of his conversion to Islam and his eventual rise to Emir of the holy city of Medina, in a society "as subtle as it is barbaric", encompassing both "the dignified simplicity of the Bedouin camp" and "the scheming, scented ante-chambers of the Viceroy's palace in Cairo".