Georges Franju's Judex is an arch, playful tribute to the serials of the influential silent filmmaker Louis Feuillade. Franju shuffles through the plot of Feuillade's lengthy serial of the same name, about an adventurer named Judex whose revenge against the corrupt banker Favraux unleashes a complicated series of schemes.

Marceau Léonetti, a competent and energetic officer stops by chance the son of an influential lawyer driving under the influence of alcohol. A few months later, the lawyer falsely accuses Léonetti as being violent and incompetent. As a result Marceau is transferred to a small police station, where he meets young and beautiful Jeanne. Soon they are faced with a tough investigation.

Somewhere in Europe, a scientific research institute, houses the lair of one of the leaders of a terrorist organization called The Black Hand. Zhan Raur, who is suffering from a delirium of power and also from a heart condition, awaits the visit of an unknown correspondent carrying precious documents. But the F.B.I. He has been replaced by one of his agents, Thomas Asher, who is responsible for unlocking the secrets and ramifications of The Black Hand.