Les Sept Boules de cristal
Michael Farr described both "The Seven Crystal Balls" and "Prisoners of the Sun" as "classic middle-period Tintin", commenting on their "surprisingly well-balanced narrative" and noting that they exhibited scant evidence of Hergé's turbulent personal life. He felt that "The Seven Crystal Balls" encapsulated the "air of doom" which pervaded the mood of Europe at the time to an even greater extent than Hergé had done in his earlier work, "The Shooting Star". At the same time, Farr thought it to be "a simple detective story", comparing Tintin's hunt for clues regarding Calculus' disappearance to Arthur Conan Doyle's stories of fictional detective Sherlock Holmes. He thought that the story was "truly Hitchcockian in its suspense and quite cinematic in its presentation", comparing the use of the music hall in the story with its use in Hitchcock's film, "The 39 Steps" (1935). Farr suggested that in the scene in which Haddock dejectedly sits around Marlinspike awaiting news of Calculus, "Hergé had allowed himself to step for a moment into Haddock's shoes and to be autobiographical".