Belmondo, who was beginning to get lucrative offers from the mainstream  film industry, ignored the warning words of his agent who told him, “you’re making the biggest mistake of your life,” and accepted the part.With his cast in place, Godard set about knocking Truffaut’s story outline into a screenplay. His original plan had been to use the outline as it was and merely add dialogue to it. Instead he rewrote the entire story, shifting the emphasis away from Truffaut’s portrayal of an anguished young man who turns to crime out of despair,  to that of a young hoodlum with an existential indifference to common morality and the rule of law.

Crucially, in the new version, the American woman Patricia  comes into the narrative near the beginning and their love story dominates the film. Filming took place over the summer of 1959. Behind the camera was Raoul Coutard, originally a documentary cameraman for the French army’s information service in Indochina during the war. Coutard’s background suited Godard who wanted the film to be shot, as much as possible, like a documentary, with a handheld camera and the minimum of lighting. This decision was taken for both aesthetic reasons – making the film look like a newsreel – and practical reasons – saving the time setting up lights and tripod.