As the movie opens, we see Camerlengo Patrick McKenna (Ewan McGregor) as he prepares to destroy the Ring of the Fisherman, which is worn by the Pope and is destroyed upon his death and before the leaders of the Catholic Church gather in Conclave to pick the new Pope. A voiceover narrates the steps that are taken for the Cardinals to be sealed in for Conclave.
At CERN (European Organization for Nuclear Research) we watch as they prepare to activate the Large Hadron Collider. Vittoria Vetra (Ayelet Zurer) confronts one of the scientists, asking why her project was taken off of the grid. He admits that they are afraid of what will happen since they have never attempted to gather so much antimatter at one time. She threatens to contact the director if he does not allow her to proceed and he concedes, but asks her not to, “blow them all up.”
As the Collider activates Vittoria contacts her research partner Silvano, and tells him to get ready. The particles accelerate and then collide and Silvano watches as the three traps activate, each containing a collection of antimatter. As he stands in awe, we see that he is wearing a priest’s collar.
Vittoria, excited, hurries to their lab, bumping into a man carrying a case through the hallway. Vittoria approaches the security door and places her face before a retinal scanner. As she stands up she feels something on her chin, wiping her chin we see that it is blood that has collected in the chin rest of the scanner. As she enters the lab she reacts in horror as she sees an eyeball lying on the floor of the lab and hears an alarm. She rushes further into the lab to see Silvano’s dead body, which is missing the eye the killer removed to gain access to the lab. She looks over to see that one of the containers of antimatter is missing.
At Harvard, Robert Langdon (Tom Hanks) is swimming laps in a pool when he sees a man enter carrying a black brief case. From the symbol on the case he realizes that the man is from the Vatican police. He tells the man that he is surprised, that he was expecting another letter. He has been petitioning the Vatican for access to their archives for years and has been consistently denied. The man is Claudio Vincenzi who explains that the Church needs his help as four cardinals have been kidnapped and they have received a letter claiming that the Illuminati are responsible. As proof, there is a picture of brand, which spells the word Illuminati, but it is an ambigram, this catches Langdon’s interest as it was thought lost. Langdon agrees to help and flies with Vincenzi to Vatican City.
When they arrive, Langdon finds out that the four men kidnapped are the Preferiti, the four Cardinals who have the best chance of becoming the next Pope. The Illuminati also threaten to destroy the Church with light, a reference to the explosion that will happen when antimatter comes into contact with normal matter and annihilates. As proof, one of the Vatican wireless security cameras has been stolen and hidden and shows the antimatter canister hidden somewhere in the Vatican. Vittoria is there and informs them that the canister’s containment field has an internal battery that will last for 24 hours; she determines from the camera that the battery will fail at midnight.
The head of the Swiss Guard is Commander Richter (Stellan Skarsgård) who is openly skeptical of the worth of having Langdon involved, especially after his involvement with the incident portrayed in the Da Vinci Code. He begrudgingly plays the message from the Illuminati, which shows the four kidnapped Preferiti in cells and threatens to kill them in revenge for the death of members of the Illuminati hundreds of years before. Langdon catches the reference to “branding” them and relates the story that the same man who created the Illuminati ambigram created four brands for each of the ancient elements, Earth, Air, Fire and Water. He also catches a reference to the Path of Illumination, which was the hidden path to where the Illuminati members would meet. The Path was a test for prospective members and Langdon says that if they can find the path, they can follow it to the four churches where the cardinals will be killed, but to do that he needs to have access to the archives. He is told that he needs the permission of the Head Archivist, who is unavailable, and Langdon reminds them that it can also be granted by Papal decree and though even the Pope is dead, the Camerlengo can grant it in his stead.
They go before the Camerlengo who expresses concern at the fact that Conclave will continue and suggests that Richter find the antimatter by systematically cutting power to sections of the Vatican and watching the monitor to see when the antimatter canister is in darkness to determine where to find it. He then asks to speak to Langdon and asks him if he believes in God, Langdon admits that he doesn’t and the Camerlengo eventually grants him access to the archives.
Langdon and Vittoria enter the archives where Langdon explains his theory that the beginning of the Path of Illumination can be found hidden in one of Galileo’s works. They find the book and carefully examine it, eventually finding the clue hidden on the fifth page of the book. Langdon attempts to read the page, but Vittoria becomes impatient and rips the page from the book saying that they don’t have time and they leave.
Langdon reads the page in the car to the consternation of Olivetti, one of the Vatican City police who requested Langdon be brought in. Olivetti is horrified that Langdon removed the page from the archives, but Langdon is successful in determining that the clue refers to the Tomb of Santi, which Langdon informs them was Raphael’s last name and he is buried at the Pantheon. They set off for the Pantheon.
They arrive and Langdon and Vittoria enter and try and find Raphael’s tomb. Vittoria calls Langdon over and shows him a plaque that states that the Pantheon wasn’t Raphael’s first resting place that the body was moved there a century after the clue was printed. Langdon quickly questions a tour guide about the original location and they set off, much to the disgust of Richter who claims they have wasted his time he orders the majority of the men back to the Vatican, leaving Langdon with Olivetti.
They set off for the other church and arrive just as the church bells chime 8 o’clock the deadline given by the Illuminati for the death of the first cardinal. Langdon and the others go into the church which is undergoing renovation and they find the “demon’s hole” which is referenced in Galileo’s clue. It leads below the church where Olivetti and Langdon discover the first cardinal who is buried to his waist in the dirt. On his chest he is branded with the Illuminati ambigram for Earth and they see that he has been suffocated by having dirt shoved down his throat.
Langdon examines the statue referenced in the clue and realizes the angel is pointing in the direction of the next point on the Path that references Air. He also realizes that the hidden Illuminati master was Bernini, who also worked for the Vatican as an artist. Following the direction indicated by the statue they head to Saint Peter’s Square.
There they hurriedly search for anything having to do with Bernini as they fight their way through a gathering crowd, which is beginning to become violent as protestors confront the religious faithful. Langdon discovers the second marker, which is a carving on the ground of the Square, but unfortunately they are once again too late as the screams of a little girl who finds the second cardinal ring out through Saint Peter’s Square.
Langdon sees that once again the marker is indicating the direction they need to go to find the third marker, but decides he needs to go back to the archives to discover which Bernini work would be considered to be about fire.
Richter and the rest of the security forces discover a new note from the Illuminati on the body of the second cardinal. The letter implies that they were responsible for the Pope’s death, which was accomplished by giving him an overdose of the medicine they were secretly taking. Vittoria informs them that such an overdose would leave evidence, but by Vatican law the Pope cannot be autopsied. Then, Vittoria receives Silvano’s journals from CERN where she believes information about who at the Vatican knew about the antimatter.
Langdon returns to the archives, this time escorted by a Vatican agent who tells him that he is there to keep watch on him to keep him from “borrowing” any more of the Vatican’s documents. They enter the vault looking for any account of Bernini’s work having to do with fire.
Meanwhile, the Camerlengo has become concerned about the safety of the rest of the cardinals in Conclave and he breaks the seals, shocking the cardinals with his interruption. He gives an impassioned speech about how they should fight the Illuminati’s lies with the truth, but he is told that they will not break Conclave. Frustrated he leaves and finds Vittoria who he asks to accompany him.
In the archives, Langdon finds the reference in Bernini’s work to fire, but as he and the agent try to leave, the power cuts out, leaving them trapped in the airtight room. As the air runs out, they make more and more desperate attempts to escape before Langdon, as he begins to pass out, uses the agent’s gun to weaken the glass of the vault wall before knocking over a heavy shelf to smash their way out. They set off for the third marker.
They arrive at the church where they see the light of flames inside. They rush in and are horrified to discover the third cardinal suspended over a large fire by chains. As the men rush to free him, the assassin emerges from the shadows and systematically kills the entire contingent from the Vatican as Langdon struggles to get away.
The third cardinal is dead and Langdon, after being rescued by firefighters and the sole survivor left by the assassin, examines a map of Rome, trying to find the fourth marker. As he plots the previous three markers he realizes that the phrase that the markers are laid “cross Rome” is literal as they form a cross. Using this he plots the location of the fourth marker, a fountain. As he rushes out of the church he is confronted by two Rome policemen who tell him they’ve been ordered to return him to the Vatican. He convinces them to help him try and save the fourth cardinal and they set off for the final marker.
Back at the Vatican the Camerlengo is leading Vittoria and members of the Vatican security to the crypt of the Pope as Vittoria informs him that an overdose of his medicine would cause the blood to pool in the mouth a week after death causing it to turn black. The Camerlengo prays for forgiveness then opens the coffin exposing the body of the Pope who does have a blackened mouth, confirming the Illuminati’s claims.
Langdon arrives at the fountains and he and the officers see a van pull up next to the fountain. The cops tell him to stay back as they approach to investigate. The assassin watches and then proceeds to kill both officers, hiding them in the back of the van. As the bells begin to chime the hour Langdon watches in horror as Cardinal Baggia, the favorite to become Pope is shoved into the water with the brand on his chest. He leaps into the water, but cannot lift the weighted frame the cardinal is strapped to. Langdon surfaces and calls for help, then frantically dives back down to see the cardinal begin to drown, Langdon pulls out one of the air lines from the fountain, giving it to the cardinal to help him breath when finally others leap into the fountain to help him lift the cardinal out of the fountain. Baggia is still alive and Langdon asks him where the assassin was hiding him, the cardinal tells him he was being kept in the Castle of Angels, which is ironic as it is right next to the Vatican.
Before leaving the Vatican, Vittoria is furious to discover that while she was with the Camerlengo examining the Pope’s body, Richter has confiscated Silvano’s journals and refuses to return them. She angrily accuses him of having something to hide and he asks her if she has anything to hide herself.
She joins Langdon at the Castle, which is being stormed by the Vatican forces. They follow the soldiers in, finding the van used by the assassin. Langdon is shocked when the soldiers hastily declare that there is nothing to be found and withdraw leaving him and Vittoria alone. Langdon begins to examine the walls looking for, and finding a secret passage.
They find the chamber with the cages that held the cardinals and the tunnel, which leads to the Vatican that the assassin used to gain access. As they continue in, they stumble across the assassin who is receiving his final instructions from his unseen employer. The assassin tells Langdon not to follow as the assassin has let him live twice since he was not paid to eliminate Langdon, but if he persists in pursuing him, he will kill them both.
After the assassin leaves, Langdon finds the box with the Illuminati brands and realizes that there is still one left that depicts two crossed keys which was meant to be used on the Pope, or in this case, the Camerlengo. Determined to save him, they set off through the secret passage to the Vatican, pausing only to stare as the assassin is killed when he is betrayed by the Illuminati and killed by a car bomb.
Back at the Vatican Richter has arranged a meeting alone with the Camerlengo, where he locks himself in. The Camerlengo calmly asks him if Richter has come to make him a martyr. Outside, members of the Swiss Guard are discussing their orders to bar anyone from entering when one hears Langdon and Vittoria banging on the hidden door to the passageway. As they begin to warn the agents they hear a scream of pain from the Camerlengo’s quarters.
The agents burst in to find the Camerlengo sprawled on the floor with the fifth brand on his chest and Richter standing over him with a gun. The guards shoot Richter who, before dying, hands Langdon a key. Time is running out on the antimatter canister, and Langdon notices that the brand on the Camerlengo’s chest is reversed, which refers to St. Peter being crucified upside down and makes them realize that the antimatter is under the Vatican where St. Peter is buried.
They hurry down, lead by the Camerlengo and find the canister as it counts down it’s final moments. Vittoria hurries to switch in a new battery which will give them another 24 hours to return the canister to CERN, but she realizes that the cold temperatures in the tomb have caused the battery to run down quicker then they thought and if she removes the batter the containment will fail instantly.
The Camerlengo shouts, “No” and grabs the canister away from Vittoria and runs out of the Vatican where he commandeers the Vatican helicopter that is arriving to aid in the evacuation of the cardinals. As Langdon and Vittoria run out they watch as the Camerlengo pilots the helicopter straight up away from the Vatican as the huge crowd in St. Peter’s Square watches on.
The containment fails and the antimatter hits the bottom of the canister causing it to annihilate which results in a gigantic explosion, which knocks the entire crowd off of their feet and causes minor damage to the Vatican. In the light of the explosion we see the Camerlengo parachuting to safety. As the crowd watches in awe, the Camerlengo comes in for a rough landing and as he is helped back into the Vatican the crowd begins to cheer.
In the Conclave the other cardinals are excitedly talking about the Camerlengo’s actions and how they believe that God wants them to make the Camerlengo Pope. They send the Swiss Guard to fetch him from the infirmary.
In Richter’s office Langdon and Vittoria are talking when she remembers the journals. She finds the compartment in Richter’s desk that holds them and when she removes them, a video screen pops out. Langdon realizes that Richter installed cameras in the Pope’s quarters to monitor his health and they recorded the entire confrontation between Richter and the Camerlengo.
Richter had discovered that Silvano, concerned over the implications of his and Vittoria’s work had contacted the Pope for guidance. The Pope was intrigued by the “God Particle” and encouraged him to keep working much to the disgust of the Camerlengo who finds the concept blasphemous. So he contrived the entire scenario to grant himself the opportunity to become the next Pope. As Richter watches stunned, the Camerlengo removes the fifth brand from the fire and applies it to his own chest, throwing it at Richter’s feet and implying Richter was the attacker.
Langdon and Vittoria show the film to the other cardinals. When the Camerlengo enters the Conclave, expecting to become the next Pope he is instead confronted by Vatican security forces that pursue him through the Vatican. Desperate the Camerlengo grabs a camera and a container of oil; he douses himself, then lights himself on fire, killing himself.
Later, we find out that the Conclave has elected the surviving Preferiti cardinal and his new Camerlengo has summoned Langdon and Vittoria. We also find out that the Church has covered up the plot, saying that the previous Camerlengo had died from his injuries sustained saving the church. As a sign of gratitude for saving his life the new Pope has gifted Langdon with the Galileo book, asking only that upon his death Langdon will it back to the church. Langdon and Vittoria watch as the new Pope dons his vestments and walks out to greet the thousands of people in St. Peter’s Square.
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