After his daughter is murdered in an apparent ritual sacrifice, Harvard astrophysicist Dr. Richard Massey travels to Chile to find the killer. There he meets Sister Josepha Montafiore, a devout nun who recruits Massey to investigate signs that point to the imminent end of the world as foretold in the New Testament's Book of Revelations. Meanwhile, Satanist Isaiah Haden has answered the Devil's call to make certain the Armies of Darkness will triumph in the apocalyptic battle to come. Together, the scientist and the nun race against the clock in hopes of averting Armageddon and proving that mankind is the master of its own fate.