"the testament of dr. mabuse" was based on elements of author norbert jacques' unfinished novel "mabuse's colony". it was lang's second sound film for nero-film and was his final collaboration with his wife and screenwriter thea von harbou. to promote the film to a foreign market, a french-language version of the film was made by lang with the same sets but different actors with the title "le testament du dr. mabuse".