Cashing In On The Code

Ellen McBreen, who runs private tours of Paris art museums, kept hearing the same question on her Louvre walkabouts: "Is this where the curator was murdered?" The curator in question, Jacques Saunire, is a fictional character in Dan Brown's ubiquitous best seller The Da Vinci Code, but her clients' interest was real and surprisingly keen. Some of the novel's "hard-core followers," McBreen remembers, came to the Louvre equipped with highlighted passages and well-researched questions.

McBreen sensed a business opportunity for her tour company, Paris Muse. In February, she started to offer Cracking the Da Vinci Code tours: 2...