In the Louvre late at night, the curator Jacques Sauniere is murdered, and his body is disfigured with strange signs. Police believe that the victim has so riddled himself. His murderer, Silas, calls to a certain Teacher to report that four people who informed him before their death the same information are removed. A certain brotherhood has created a cornerstone on which are encrypted some characters that hold the secret of this brotherhood. All those killed showed that the map is in the Parisian church of Saint-Sulpice. The Teacher urgently demands to get this map.
Police appeal for help to a professor of religious symbology, Robert Langdon, from the Harvard University. Bishop Aringarosa, the father-chairman of the brotherhood of "Opus Dei", flies from New York to Rome. Recently, a special group has been watching after the brotherhood, since some of its members have been seen in wrongful deeds, but the Brotherhood is under the auspices of the Vatican. Recently, some members of the brotherhood were attacked. Aringarosa receives news that Silas has found the cornerstone.
Langdon arrives in the Louvre at the crime scene. According to police, Sauniere was in his office when he was attacked. He ran into the gallery and turned on the alarm, tearing the painting off the wall. The entrance to the gallery was blocked by the grill, and the killer shot at the curator through it. Sauniere crawled quite a distance and died. Police found him naked, lying on his back with outstretched arms and legs. In the center of the belly was painted five-pointed star - pentacle. In the darkness, beside the corpse purple letters and numbers were visible. The murderer disappeared.
The sister of Saint-Sulpice Church Sandrine meets a representative of "Opus Dei", who has arrived in Paris. Trying to decipher the writing, Langdon finds that Sauniere with his posture copied the famous painting by Leonardo da Vinci's "Vitruvian Man". The captain Bezout Fache transmits pictures with characters to cryptography department, and cryptographer Sophie Nёve comes to the crime scene. She informs Langdon that he is in danger. Aringarosa meets with Silas, whose life he once saved, and with the Teacher.
Sophie tells Fache that the set of digits is Fibbonachchi sequence. Having a moment alone with Langdon she tells him that he is the first suspect in the murder, so in his pocket a special beacon tracking has been slipped. Apart from secret characters written beside the body, there was an inscription that Fache wiped: Sauniere asked to find Langdon. The inscription was meant not for the police, and for her, as she is Sauniere’s granddaughter.
Sophie was left an orphan at four years. Her parents, grandmother and younger brother died in a car accident, and the girl has been brought up by her grandfather. Ten years ago, returning home without warning, she found her grandfather in a society of strange people who worshipped some object and performed strange rituals. Sophie broke off relations with him. Since then they have not seen, but her grandfather asked her for a meeting.
With Sophie’s Langdon manages to escape from the Louvre. Having carefully reread the record, Langdon finds that it is an anagram of the words "by Leonardo da Vinci's Mona Lisa," and the Fibonacci sequence is a cipher. Sophie remains in the Louvre. She wants to find "Mona Lisa" and find out what the mysterious message her grandfather has left. Silas comee to the church of Saint-Sulpice. He asks Sandrine to leave him alone, to pray. Hiding, Sister Sandrine is watching him.
Sophie arrives to the crime scene. Langdon does not escape but returns to her. Havong thought it over he had come to the conclusion that in an inscription near the deceased was encrypted a symbol of a secret society that Sophie must have once seen at her grandfather’s. After examining the glass on the painting "Mona Lisa", they see the sign of blood - one of the fundamental principles of brotherhood.
Sophie examines another picture of Leonardo da Vinci "Madonna of the Rocks." There she finds an unusual key that she once saw as a child, and that is to open the box with a lot of secrets. On the key they see the address. Langdon is arrested by Louvre security agent, but Sophie saves him.
Silas, thinking that he is alone gets from a hiding place the Bible to find out where the cornerstone is. Sister Sandrine calls members of the brotherhood and finds out that they are killed. Finding nothing, Silas kills sister Sandrine.
Sophie and Langdon escape from the police. Langdon tells of the brotherhood called "Priory of Sion", which is marked with the seal of the key. Templars passed to the brotherhood important secret documents, which they had brought from Jerusalem to Europe, which contain the information about the Holy Grail. Aringarosa had received a considerable sum of money from the Vatican.
As indicated on the key address leads them to the Swiss bank. Sophie and Langdon find a safe, but don’t know the account number. The president of the bank knows that they are suspected of the murder, their pictures have already been distributed by Interpol. Sophie tells him what has happened. The police come to the bank. The president Berne agrees to help, he does not want any trouble in the territory of the bank, and Sauniere was his friend. Langdon remembers the inscription near the dead body - it is the account number.
The safe contains a box with a symbol of the Priory of Sion on its lid. Taking the casket with him, Bern leads them from the bank. Silas repents to the Teacher that did not fulfill the task, but he soothes him, as knows who Sauniere transferred the information to.
Inside the box they find the cryptex, cylinder drives. The cryptex was invented by Leonardo da Vinci, but Sauniere loved to cut these things out of wood. Upon reflection and learning from Sophie about the rite, which she saw as a child, Langdon comes to a conclusion that Sauniere was one of the members of society who are entrusted with a secret, and the given cryptex contains the information of where the Holy Grail is. There should be more people dedicated to the secret. Sauniere apparently felt danger, if he wanted to entrust the secret to her granddaughter and to him.
Having heard on the radio that Sophie and Langdon are accused of killing three more people, Bern requires them to give back what Sauniere confided to his guard. Sophie and Langdon escape, leaving Berne alone in the forest. Langdon realizes that a traitor has got into the Brotherhood. He decides to turn to the outstanding scientist Leigh Teabing, who has been studying the Holy Grail. Teabing would get interested in the cryptex and would not give them up to the police.
After listening to Sophie and Langdon, Teabing shows them a picture of Leonardo da Vinci's "Last Supper." Each of the thirteen participants has his bowl, but the Bible and other legends believe that the Holy Grail has appeared here. Teabing believes that the grail is not an object, but a person, a woman, as the vessel is a symbol of femininity. The woman is depicted on the painting, and she is Mary Magdalene.
According to various documents and ancient scrolls of the Dead Sea, Jesus and Mary Magdalene had a romantic relationship, they were husband and wife. Blood in the Holy Grail is the child of Jesus, Mary Magdalene was carrying. The church hid this fact and declared Mary Magdalene a prostitute, but that was not true.
To save the child Mary fled to France and gave birth to a baby girl Sarah. Documents about the life of Jesus, Mary and Sarah were buried and found by the Templars. The search for the Holy Grail is the search for the tomb of Mary Magdalene. Jesus’s kin had been developed, allied with a native French kings who had founded Paris.
Teabing’s servant Remy informs the owner that Langdon and Sophie are wanted by the police. So Teabing would not give them up to the authorities, Langdon shows him the cryptex. Silas, who has crept under his window, sees this. Meanwhile, to Teabing’s house comes police. Upon reflection, Teabing, Langdon and Sophie come to the conclusion that Sauniere gave the secret of the brotherhood to Sophie, as the rest of those who knew it were killed. The killer must have been sent by the Church.
Teabing is studying the cryptex, and Langdon and in another room is examining the box. He finds in it a piece of wood with an inscription in an unknown language, but then Silas hits him on the head. Threatening Sophie and Teabing with a gun Silas demands to give him the cryptex. Teabing knocks the gun off. Police burst into the house, but Teabing, Remy, Sophie and Langdon, taking Silas with them, manage to escape. Is unclear how Silas could have found them.
Teabing offers to fly to England on his plane. After thinking about the cryptex, they decide that it is important to find the grave of the Templars, and the encrypted word is Sofia. The cryptex contains another cryptex together with a note stating that one needs to find a grave of a knight buried in London by the Pope, and to take the ball there. Hearing the news, Aringarosa understands what he drew Silas in, and decides to fly to London.
Deceiving the British police, Teabing, Langdon, Sophie, Remy and Silas go to the knight's grave in a church where the Templars are buried. While Teabing, Sophie and Langdon are in the church, Remy, who works for the Teacher and expects to receive a large sum, frees Silas. Silas bursts with a gun, demanding to give the cornerstone. Langdon threatens to break up the cryptex. Then Remy puts a gun to Teabing’s temple and Langdon gives the cryptex. Remy takes Teabing away and lets Sophie and Langdon go.
Teabing’s house is searched by the police. It turns out that his servant Remy was once involved in petty theft. Sophie reports to the police about the abduction of Teabing. She is talking with Captain Fache. He apologizes for the charges and wants to meet with them. The Teacher calls Silas and asks Remy to bring the stone to him to the residence of "Opus Dei". In the Research Centre of the Royal Library, Sophie and Langdon meet librarian Pamela Ghetto.
Leaving Remy with Teabing in the car, Silas comes to the residence. The Teacher comes, who has not been seen by anyone before, comes to the car. He kills Remy and takes the cryptex.
Pamela studies the documents and comes to the conclusion that a knight is Isaac Newton, Grand Master of the Priory of Sion, who has been cursed by the Church. Newton was buried in Westminster Abbey by the philosopher Alexander Pope. At the residence of "Opus Dei" Silas is arrested. During his detention, he resists and accidentally injures bishop Arangarosa.
Sophie and Langdon come to the Newton's grave. The hiding Teacher sees them. Sophie and Langdon see the inscription on the tomb, which tells where Teabing is. In this place they find Teabing holding a gun. This is the Teacher, who has organized the murder of Sauniere, Sophie's family and other people, so no one knew the secret of the Grail. Teabing staged conversation with Remy and Silas, deceiving them. Now he wants to take the possession of the cryptex secret.
Silas drags the wounded bishop, so he is helped. A few months ago, Aringarosa suggested that "Opus Dei" came out of the Vatican’s custody. When the bishop refused, Teacher called him and offered to assist in the search for the sacred relics. Bishop regrets that ordered Silas to listen to the Teacher. Trying to outwit each other, Teabing and Langdon understand what the ball on the grave means - an apple. But then the police arrests Teabing. Silas dies from his injuries.
Langdon and Sophie go in Scotland, to the church, the last entry in the cryptex indicates to. There they meet a woman who has exactly the same casket. The woman is the grandmother of Sophie, who for many years lived under a different name. With the grandmother lives the younger brother of Sophie. The grandmother and brother did not go in the car, and then after the incident have been forced into hiding. Sophie got a family, and Langdon had to leave. They agree to meet soon in Florence.