Angels & Demons is a 2000 bestselling mystery-thriller novel written by American author Dan Brown and published by Pocket Books and then by Corgi Books. The novel introduces the character Robert Langdon, who is also the protagonist of Brown's subsequent novels - The Da Vinci Code, The Lost Symbol, Inferno, and Origin. Angels & Demons shares many stylistic literary elements with its sequel, such as conspiracies of secret societies, a single-day time frame, and the Catholic Church. Ancient history, architecture, and symbolism are also heavily referenced throughout the book.