Marc is a French secret agent whose only weapons are judo and karate. With the help of his sidekick Jacques, the duo goes to protect a noted scientist from falling into the hands of a gang of underworld thugs. Marc finds love with one of the female gang members who turns out to be a double agent with the British Secret Service.
| Actor | Role |
|---|---|
| JJean-Claude BercqMarc Saint-Clair, aka 'le Judoka' | Marc Saint-Clair, aka 'le Judoka' |
 Marilù ToloVanessa | Vanessa |
 Perrette PradierDominique Berg | Dominique Berg |
 Patricia ViterboCatherine Demange | Catherine Demange |
 Michael LonsdaleThomas Perkins | Thomas Perkins |
 Henri GarcinJacques Mercier | Jacques Mercier |
 Mick BessonOscar Meyer, sound engineer | Oscar Meyer, sound engineer |
 Fernand BersetCommissioner Chaumont | Commissioner Chaumont |
 Yves BrainvillePaul Vincent, the boss with the glass eye | Paul Vincent, the boss with the glass eye |
| DDavid TonelliNot listed | Not listed |
| CClaire ChevalierThe young singer (uncredited) | The young singer (uncredited) |
 Georges GuéretThe mariner (uncredited) | The mariner (uncredited) |