The provided excerpts introduce Dan Brown’s thriller, "The Last Secret: A Robert Langdon Thriller," highlighting the return of the Harvard symbology professor. The narrative begins in Prague and rapidly accelerates when Langdon's companion, scientist Katherine Solomon, vanishes, forcing him into a desperate search for her and a pivotal manuscript while being pursued by authorities. The plot is characterized by Brown's signature formula, including a race against time, a focus on symbols and historical mysteries, and the exploration of themes like noetic science and consciousness.