A cabaret singer in Barcelona sacrifices her feelings for an exiled young Frenchman who had been falsely accused of a crime, when the sister of the real culprit seeks the exile out.
Belphégor deals with a series of mysterious appearances by a masked-and-robed figure in the Louvre; a security guard is murdered, and a later police trap is foiled when the phantom—“Belphégor” (the name of a legendary demon)—uses knock-out gas. Journalist Jacques Bellegarde of “Le Petit Parisien” (the real-life newspaper which published the original story in serial installments), investigates, and eventually discovers famous detective Chantecoq and his vivacious daughter Colette are also on the case.
Bicard nicknamed Le Bouif earns 1,000 francs for lending his body to the experiments conducted by Professor Caligari. Further adventures await him when he encounters Ladislas, a young reveler, who happens to be the crown prince of Corinthia. This one, who favors living it up over his royal duty, commissions Bicard to replace him on the throne.