The novel begins with the murder of Leonardo Vetra in his private quarters in the CERN Particle Physics Laboratory. Vetra and his daughter Vittoria are working together on a very important project involving the creation of antimatter. His body is discovered to have been branded with the ambigram symbol of the long-dead group called the Illuminati. This is where the protagonist, Robert Langdon, enters the story. He is a professor at Harvard University and his specialty is symbology. Having written and researched the Illuminati group, Langdon is somewhat of an expert and is called in to help solve the murder. He is contacted by the director of CERN, Maximillian Kohler. After Kohler, Vittoria, and Langdon enter Vetra’s lab, Vittoria realizes that the largest sample of antimatter had been stolen, and the special canister used to contain the particles has a back up battery of only 24 hours. After this time the antimatter will collide with the canister and self destruct. It is revealed that the stolen canister is hidden somewhere in Vatican City, with a security camera showing how much time is left before mass destruction. So Langdon and Vittoria travel to the Vatican, where they are reminded that the pope had died, and the ceremony to elect a new pope, the papal conclave, is about to begin. In the papal conclave, four cardinals are chosen to be voted on by the rest of the cardinals who have gathered at St. Peter’s Basilica. The four Preferiti , as they are called, are missing when the ceremony begins, and all man power of the Swiss Guard is spent trying to find them rather than the antimatter canister. In effort to find the lost cardinals, Langdon follows the “Path of Illumination”, a trail used by the Illuminati to bring in new members the the headquarters in ancient times. There are four “symbols” of the Illuminati: Earth, Air, Fire and Water. Accordingly, there are four churches on the Path, and each one gives clues to lead to the next, if you know what you are looking for. As Langdon deciphers the clues he reaches each church too late; at each, one of the Preferiti had been killed according to which symbol that murderer branded into their flesh. For Earth, the cardinal was buried and had soil forced down his throat until he suffocated. The next cardinal, representing Air, had his lungs punctured. For Fire, the cardinal was burned alive, and finally the cardinal branded with the symbol for water was drowned. Langdon was not able to save any of the cardinals. They meet the assassin, who is working for the Illuminati leader named Janus. Vittoria is kidnapped by the assassin and Langdon is almost killed, but he continues on the find the last church in order to find the antimatter and save Vittoria. Langdon is able to save Vittoria and kill the assassin, but they still have to find the antimatter and time is running out. It is feared that Kohler is actually Janus, and the Swiss Guard shoot him. As he is dying, he gives Langdon a tape that he says will explain what is going on. The late pope’s aide Camerlengo Ventresca had what he calls a vision from God as to where the antimatter is hidden, and it is found deep in the catacombs. With five minutes left on the battery, they bring it into the helicopter, and the Camerlengo parachutes out as the canister explodes in midair, after which he is considered for the position of Pope. Langdon ends up on Timber Island with minor injuries. The videotape is then viewed, which reveals that Leonardo Vetra had met with the Pope to talk about his research and how it could link religion and science, which excited him because he was a devout Catholic. The pope admitted to his appreciation for science because it gave him a son. The camerlengo, who does not know he is the pope’s son by artificial insemination, disagrees with the pope breaking his vow of chastity and creates this intricate plan to set things right. It was he who poisoned the pope, and acted as Janus. He planted the antimatter and kidnapped the cardinals. When the camerlengo learns who his father was, he is guilt-ridden and sets himself on fire in front of a crowd in the city. For his help, Langdon is given the Illuminati Diamond brand.