Antiquarian Harry Blake is asked to translate an old diary written in cryptography. Having barely started work, he receives an offer from a certain Cassandra to sell her a manuscript, but refuses. After Blake is attacked, he decides to return the manuscript to its owner, only to find out that he has been killed. Why does an ancient manuscript evoke such passions? Trying to unravel this mystery, Blake plunges into a world of deadly secrets, church and political intrigue. He learns about the existence of a Christian shrine, which is being hunted by terrorists in order to use it to start a new holy war. Information about the location of the shrine is encrypted in the diary. Will Blake be able to solve this puzzle and prevent disaster?