A counterfeit 500-franc note changes hands through a series of transactions in Paris, starting with a disobedient schoolboy who uses it to settle his debt at a photography shop. The shop owner, upon discovering the false bill, knowingly passes it along to an unsuspecting deliveryman, Yvon, as part of his payment for a regular delivery. Yvon is caught when he tries to use the counterfeit money at a restaurant. This incident initiates severe consequences for him, leading to his wrongful termination from his job.

Yvon’s life spirals downward as he struggles to prove his innocence and support his family amidst the unjust accusations. His desperation drives him to make increasingly drastic decisions, which entangle him further in a cycle of crime and punishment. Each encounter Yvon has with society underscores themes of greed, betrayal, and apathy, reflecting on how one small act of dishonesty can devastate numerous lives. The narrative explores the interconnectedness of individual actions and the often harsh consequences they can provoke in an unforgiving social structure.