Andalucia, 1938 - towards the end of the Spanish Civil War, a group of Republican soldiers kidnap Professor Pinzon and his grandson and hold them hostage in St Jaime's Cathedral together with a group of townspeople. Searching the Cathedral, they discover a crypt leading into a secret space, a medieval mosque directly underneath them, undisturbed for hundreds of years. The mosque holds a book, written in the eleventh century by Samuel the Jew. Reading it to his grandson, the Professor realises that Samuel's tale - a story of lifelong friendship, love, and religious warring between Christians, Muslims and Jews in medieval Spain - has anticipated many of the events in the ideologically torn world of the mid-twentieth century. And in its description of the building of the mosque, Samuel's tale may also hold the secret to freedom for the hostages . . .