After the mysterious death of one Vatican priest and the disappearance of another, Father Ian Pearse, an American working on ancient Christian texts in the Vatican, comes into possession of a mysterious scroll. He discovers ingeniously coded letters and the text of an ancient Manichean prayer that has never before been found in written form. These reveal a Manichean conspiracy - a sect long-thought dead - reaching deep into the present Vatican hierarchy. Racing from the Vatican via an ancient Greek monastery to war-torn Bosnia, Father Pearse has to decipher the cryptograms and codes before the closely guarded heresy is unleashed on the world.