A fabulous, bejeweled chess set that belonged to Charlemagne has been buried in a Pyrenees abbey for a thousand years. As the bloody French Revolution rages in Paris, the nuns dig it up and scatter its pieces across the globe because, when united, the set contains a secret power that could topple civilizations. To keep the set from falling into the wrong hands, two novices, Valentine and Mireille, embark on an adventure that begins in the streets of Paris and leads to Russia, Egypt, Corsica, and into the heart of the Algerian Sahara.
