Inferno is a 2013 mystery thriller novel by American author Dan Brown and the fourth book in his Robert Langdon series, following Angels & Demons, The Da Vinci Code and The Lost Symbol. The book was published on May 14, 2013, ten years after publication of The Da Vinci Code (2003), by Doubleday. It was number one on the New York Times Best Seller list for hardcover fiction and Combined Print & E-book fiction for the first eleven weeks of its release, and also remained on the list of E-book fiction for the first seventeen weeks of its release. A film adaptation was released in the United States on October 28, 2016.

Origin is a 2017 mystery thriller novel by American author Dan Brown and the fifth installment in his Robert Langdon series, following Inferno. The book was released on October 3, 2017, by Doubleday. The book is predominantly set in Spain and features minor sections in Sharjah and Budapest.