Indy and his girlfriend, Nancy Stratemeyer (whose father created the Nancy Drew mystery series) visit the fascinating laboratory of inventor Thomas Edison and they must contend with dangerous German spies, as they try to keep Edison's top-secret invention safe.

On a visit to Vienna, young Indy and his family stay with the American Ambassador in Austria where Indy meets Princess Sophie, the daughter of the heir to the throne, Archduke Franz Ferdinand and is given some advice on the meaning of love from Sigmund Freud, Carl Jung and Alfred Adler.