A codex of secret knowledge, dictated by Jesus of Nazareth as he awaited crucifixion, arrives at the Pontifical Biblical Institute in Rome. The task of separating and deciphering the rust-encrusted lead/copper plates falls to the Institute's Professor of Hermeneutics, ex-priest Thomas Constantine. As the American-born Constantine begins the authentication process, fate makes it personal. An international dealer in black-market antiquities steals the artifact and kidnaps Constantine's fiancé. The codex leads Constantine from a forest deep in the Tiber Valley to a pitch-black tunnel in the labyrinth-like bowels of the Roman Colosseum where he must decide: obliterate the roots of his religion or ignite a jihad the likes of which the world has never seen. Which will he choose?