Dan Brown's novel "The Da Vinci Code” is one of the century’s most successful thrillers worldwide. But how much truth is behind the claims made in the book - and what is pure fiction? The novel "The Da Vinci Code” by American author Dan Brown has sold around 80 million copies since its publication in 2003. The film adaptation starring Tom Hanks in the lead role was also a global success. Thematically, the thriller moves between art, mysticism, religion, and conspiracy theories. But the theories presented in both the book and the film adaptation also drew criticism, especially from the Catholic Church. Some religious groups even called for a boycott.