After the death of the Pope, the conclave has gathered in a locked room to choose his successor among four cardinals designated "preferitti". However the quartet is abducted by the Illuminati, a secret brotherhood that was supposed eradicated. The symbologist Robert Langdon and the scientist Vittoria Vetra, who had her powerful and dangerous prototype of antimatter research stolen, are invited by the Vatican police to help them in their investigations. They are received by the receptive Camerlengo, Patrick McKenna, and by the reluctant Commander Richter. They are informed that the Illuminati have promised to kill each cardinal every hour from 8:00 PM and then blow up Vatican City with the antimatter. Robert and Vittoria have a few hours to unravel the clues and discover where the lethal weapon might be hidden.