Professor Johnston, known familiarly as “the professor,” is a Regius Professor of History at Yale University. He is over 60 years old and is tall and fit. He is the leader of the archaeological dig in the Dordogne and the supervisor of the five graduate students. He has a “sardonic” manner and is compared to Mephistopheles, the strong, arrogant assistant of Satan from the classic legend of Faust. Johnston is strong-willed and savvy. When he realizes that ITC has information about the archaeological dig that they do not, he insists on meeting with Doniger immediately, in person, and seeing the technology firsthand. He is also canny enough to leave a message for his team when he becomes stranded in 1357.

With his extensive knowledge of medieval history, Johnston is able to blend in relatively easily with society in the 14th century. For example, he ingratiates himself with the nobility and the clergy as a Magister, which is a Latin term for “teacher” in the medieval ages. He uses his new position to search the monastery’s archives for the secret passage into La Roque. However, this position of knowledge also puts him in danger as the two sides try to gain control of him to find out what he knows about the passage and advanced military technology.