Dan Brown's novel "The Da Vinci Code" is a mystery thriller that follows symbologist Robert Langdon as he investigates a murder in the Louvre Museum in Paris. The story intertwines art, history, and religion, leading Langdon and cryptologist Sophie Neveu on a quest to uncover secrets hidden in famous works, including those of Leonardo da Vinci. The novel explores themes of faith, conspiracy, and the interpretation of historical symbols. As Langdon and Neveu decode clues, they confront powerful organizations and challenge established beliefs, ultimately revealing a controversial theory about the life of Jesus Christ and the Holy Grail.