It is fall,1906, near Avignon in the south of France. Renowned archaeologist Claude-Henri Fillon has just made a startling and disturbing discovery - a Roman artifact that could undermine Christianity itself. Fillon summons his friend and former student, Gerard de Montclaire, France's greatest detective, to advise him and to safeguard the discovery but too late. The artifact has been stolen, one of Fillon's assistants is missing, and another student is dead. Montclaire and his associate, Sir Francis Fitzmaurice, must find the priceless artifact and a cunning murderer who appears to have taken it. Unraveling this mystery will lead the pair into an ancient and ruthless conspiracy.