After Jacques Saunière, the curator of the Louvre museum, is found murdered inside the famed museum, Harvard professor Robert
Langdon is asked to assist in the investigation, beginning with the cryptic messages and bizarre placement of the body.
Police cryptographer Sophie Neveu, who is Saunière’s granddaughter, arrives on the scene reveals to Langdon that he is a prime suspect in the murder and that her grandfather identified him by name in another cryptic message. After agreeing to team up to uncover the mystery of the murder, Sophie and Langdon escape the French police and begin their search. They find a golden key and use it to open a Swiss bank safety deposit box at. Inside the box is a device called a cryptex which is used to store
secret documents. The pair’s investigation leads them to the country estate of renowned British historian and colleague of Langdon, Leigh Teabing, who offers them more information about the history of the Grail. Teabing claims that the Grail is not an object, but rather, a long-suppressed secret: that Jesus Christ was married to Mary Magdalene and had at least one child with her. He also tells them that Saunière is the leader of a secretive group, called the Priory of Sion, charged with the responsibility of protecting this secret.
Throughout this whole time, the albino monk responsible for Saunière’s death follows them in order to uncover or protect details about the secret. He also attacks them at several points in the story. After teaming up with Teabing, Sophie and Langdon fly to London on Teabing’s private jet. They follow a sequential series of clues found in the cryptex, all of which lead to more clues. At this point it turns out that Teabing’s servant is involved in some conspiracy, kidnaps Teabing, and steals the cryptex. Sophie and Langdon research the remaining clues, eventually arriving at Westminster Abbey to seek the answer to one of the final puzzles stored in the cryptex. It is finally revealed that the mastermind behind the killing of Saunière was actually Teabing who faked his own kidnapping in order to complete the ruse. After a long stand-off with Langdon and Sophie, the police arrive and arrest Teabing. The remaining clues lead Sophie and Langdon to an ancient church in Scotland where they find the grandmother and brother that she had long believed were dead. Sophie is, in fact, the heir to Christ’s royal bloodline, and her family was divided and denied knowledge of one another in order to protect and conceal their true identities. At the conclusion of the novel, Langdon finally recognizes that the Grail is buried beneath the glass pyramids at the entrance of the Louvre. He allows the secret to remain hidden.