At the Louvre, an Opus Dei monk named Silas captures Jacques Saunière, the museum's curator, and demands to know the whereabouts of the Holy Grail. After Saunière tells him, Silas shoots him and leaves him to die. However, Saunière lied to Silas about the location of the Grail. Realizing that he only has a few minutes left to live and that he must reveal his important secret, Saunière paints a pentacle on his belly with his own blood, draws a circle with his blood and drags himself to the center of the circle, re-creating the location of Da Vinci's Vitruvian Man. He also leaves a code, a line of numbers, and two lines of text on the ground in invisible ink. A police detective, Jerome Collet, calls Robert Langdon, the protagonist of the story and professor of symbology, and asks him to come to the Louvre to try to interpret the scene. Langdon still doesn't realize that he himself is a suspect in the murder. After killing Saunière, Silas calls the "Master" and tells him that, according to Saunière, the keystone is in the church of Saint-Suplice in Paris. The Master sends Silas there. Silas follows Saunière's clues to the location of the keystone and discovers that he has been deceived. In a fit of rage, he kills Sister Sandrine Bieil, caretaker of the church and sentry of the Priory of Sion. At the Louvre, Langdon meets Jerome Collet and Bezu Fache, the police captain, and realizes that the two policemen suspect him of the murder. Sophie Neveu, an agent of the cryptology department and Saunière's niece, arrives at the crime scene and informs Langdon that he must call the embassy. When Langdon calls the number Sophie gave him, it reaches his voicemail. The message warns Langdon that he is in danger and that he should meet Sophie in the Louvre bathroom. In the bathroom, Sophie shows Langdon that Fache is recording her movements with a tracking device. He throws the device out the window onto a passing truck, fooling the police into thinking Langdon has escaped from the Louvre. Sophie also tells Langdon that the last line of the secret message, "PS Find Robert Langdon", was her grandfather's way of warning her: PS are the initials of the nickname her grandfather gave her, Princesse Sophie. Langdon thinks PS might stand for Priory of Sion, an ancient brotherhood dedicated to preserving the tradition of pagan goddess worship and maintaining the secret that Saunière died protecting..