The story tells the investigation started by symbolist Robert Langdon and a good-looking cryptologist, Sophie Neveu, around the murder of a Museum Louvre's curator. In fact, the unfortunate murdered man was Sophie's grandfather, and the corpse was found with a series of symbols and codes, like a pentagram and a Fibonacci number sequence. But police detective Fache will begin to chase Langdon, who escapes after receiving a warning about the captain's real intentions. Sophie has with her a kind of key with dots and number 24 engraved on it, which opens to her and Langdon a big complex investigation that involves a supposedly heretic theory: Jesus Christ and Mary Magdalene were, in fact, a couple who produced a daughter named Sara. A millenarian sect called The Priory of Sion has kept for centuries the secret of that matter. A masochist and kind of psychopath albino monk, Sibilas, an Opus Dei member, will chase Langdon and Sophie as well, in order to impede that they solve the mystery of Christ and Mary Magdalene, and also the real meaning and location of the Holy Grail. A passionate British researcher, will help Langdon in his quest, revealing to them several symbolisms in Da Vinci's master work The Last Supper, traveling to mythical places in the UK, such as The Church Temple, where it is believed that a group of Templars Knights are buried, and Sir Isaac Newton's tomb at Westminster Abbey, where are located some of the main keys to solve the Holy Grail's mystery.