1203. Constantinople is besieged... by the Christians of the 4th Crusade! Under cover of night, a small group of knights flees the doomed city. They're taking three mysterious chests to Antioch - but never reach their destination. Nowadays, in Rome, Agent Reilly has come with a Professor Sharafi to request access to the Vatican's archives. But once inside, he reveals that the document they're here to consult is one that the Church doesn't want anyone to see...