This thriller novel follows symbologist Robert Langdon and cryptographer Sophie Neveu as they investigate a murder in the Louvre Museum in Paris. The murder leads them to a trail of clues hidden in the works of Leonardo da Vinci, revealing a religious mystery protected by a secret society for two thousand years. The mystery involves a conspiracy within the Catholic Church and threatens to overturn the foundations of Christianity.

In "Old House of Fear," the protagonist, an American envoy, travels to a remote Scottish island to negotiate the purchase of an old mansion. Upon arrival, he encounters an atmosphere of mystery and terror, fueled by local superstitions and the eerie presence of the mansion itself. As he delves deeper, he faces a series of supernatural occurrences and a sinister conspiracy, challenging his skepticism and forcing him to confront his deepest fears. The novel blends elements of Gothic horror with a modern psychological thriller, creating a gripping and suspenseful narrative.