In the darkness of 13th Century Europe, the most precious treasures of the Christian world lie in a small church in the great ruined city of Constantinople: the crown of thorns, the spear that pierced Jesus' side, the shroud bearing the imprint of Christ. On the other side of the globe, Petroc of Auneford sails into the sprawling Pool of London for the first time. He has left his old monastic world behind for that of the enigmatic Captain de Montalhac - purveyor of fine relics and other exotic trinkets to anyone with sufficient money and desire. For Petroc, the trip is soon blighted by tragedy, but grief is no guard against greed or rumour. The great powers of Christendom are gathering - all covet the power of the most precious relics - and Petroc finds himself right in the eye of the storm.