Belphegor

The success of the pulp mystery series Fantämas, launched in 1909, inspired many successors including Arnould Galopin's Tenebras (1911), Gaston Rene's Masque Rouge (1913), and Arthur Bernede's Judex (1917), co-created with film director Louis Feuillade. In 1927, Bernede produced another simultaneous book and film project -- Belphegor.
Belphegor concerns its eponymous criminal mastermind, a hooded maniac whose name derives from a malefic demon, and who is obsessed with retrieving the lost treasure of the Medicis from its ancient burial-place.
Only Chantecoq, the "king of detectives", aided by a news reporter and his own daughter, can hope to unveil the sinister and sadistic figure that nightly haunts the Paris Louvre and its catacombs with a hunchbacked henchman, the pair dealing death, panic and confusion to any that stand in their way.
And with that unveiling comes one of the most stunning twists in the genre to that date.
Belphegor was also made into a highly successful 1960s serial for French televison, and a feature film entitled The Curse Of Belphegor. More recently it was filmed as Belphegor, Phantom Of The Louvre (2001), which also generated an animated television series. It remains one of the key works of early French pulp fiction.