[1] He is a Harvard University professor of Religious Iconology and Symbology (a fictional field related to the study of historic symbols, which is not methodologically connected to the actual discipline of semiotics).

On the acknowledgments page, Brown calls Langdon "one of the most ingenious and gifted artists alive … who rose brilliantly to my impossible challenge and created the ambigrams for this novel".

Langdon is later joined in the investigation by Vittoria Vetra (Leonardo's adopted daughter) and they start their journey to the Vatican to unlock the mystery behind the Illuminati, an anti-Catholic secret society which, according to the plot, has deeply infiltrated many global institutions, political, economical and religious.

Langdon spends the rest of the novel dodging the police and trying to solve the mystery of an ancient secret society, the Priory of Sion, which was once headed by Leonardo da Vinci.

Slightly before the moment he discovers the final resting place of the Holy Grail, he is seen in a romantic light by Sophie Neveu, and two agree to meet again in Florence, where Langdon will be for a lecture.

Langdon travels from Florence to Venice, and Istanbul with Doctor Sienna Brooks to prevent a biological attack by looking for a deadly virus that was planted by a client of a shadowy consulting group called The Consortium.

In the course of this, Langdon must decipher clues employing allusions to the works of Sandro Botticelli, Giorgio Vasari and Dante Alighieri, the writer of Inferno, the first chapter of the epic poem The Divine Comedy, around which much of the plot revolves.

[14] Langdon arrives at the ultramodern Guggenheim Museum Bilbao to attend a major announcement—the unveiling of a discovery that "will change the face of science forever."

The evening's host is Edmond Kirsch, a forty-year-old billionaire and futurist whose dazzling high-tech inventions and audacious predictions have made him a renowned global figure.

Navigating the corridors of hidden history and extreme religion, Langdon and Vidal must evade an enemy whose power seems to emanate from Spain's Royal Palace itself, and who will stop at nothing to silence Edmond Kirsch.

On a trail marked by modern art and enigmatic symbols, Langdon and Vidal uncover clues that ultimately bring them face-to-face with Kirsch's shocking discovery.

The book Christianity and the Sacred Feminine, mentioned in Origin had reportedly been denounced by the Vatican, "which, in the aftermath, promptly became a bestseller", as quoted by the AI assistant Winston.