A schoolmaster known only by the derogatory nickname favored by his students—Sourpuss—has reached a point well beyond burnout when it comes to trying to teach anything of lasting value to a class filled with boys for whom rowdy seems peculiarly quaint. The boys who refer to him with such disrespect is on his last nerve after so many interruptions, so much graffiti on the walls and more than enough pornographic images being passed from boy to boy. All his pent-up anger and resentment explodes in the shouted rhetorical inquiry: “What will France be like ten years from now?”
One of the least deserving students to which Sourpuss appends the decline and fall of French society over the next decade is young Antoine Doinel. The vitriol that the teacher spews forth at his students does not take into consideration such realities of cause and effect as the fact that Antoine comes to school from a home where the soundtrack is the sound of his parents fighting. The last words Antoine hears from mother most nights aren’t “good night, I love you” but “take out the trash.” His parents have succeeded in few things in their lives, but one task they have both mastered is making Antoine feel unloved, unwanted and unlike to succeed any more than they have.
As a result of the misery that is both home life and school life, Antoine is driven to run away from both. On one of these occasions, he is joined by his friend Rene on a visit to a theater and an amusement park. As he heads home for the evening, he spots his mother kissing a man who is not his father and she spots him discovering her secret. Neither is particularly eager to disclose the other’s secret. He makes an attempt at forging his mother’s handwriting so his absence will be excused, but gives up and burns the note. When his father gets home from work, Antoine fabricates an entire day of adventure, but never mentions having seen his mother. His mother’s late arrival prompts his father to launch into accusations that she has been cheating on him.
The next day at school Antoine learns that another boy has ratted out his day off to his parents. When a teacher makes an inquiry about why he wasn’t in school the day before, he gains sympathy by lying about how his mother died. That jig is quickly up when his parents show up at school in a rage.
The breaking point in his relationship with institutionalized education comes when he’s caught plagiarizing. The crime is compounded by the fact that he plagiarize just any writer, but one of the national treasures of France, Honore de Balzac. Fresh from quitting school, he makes plans to finance running away from home by stealing a typewriter from where his father works, but gets caught for that crime as well and is turned over the police by his infuriated father.
Antoine spends a night in jail alongside hookers, thieves and assorted thugs and low-life criminal types. Antoine’s mother arrives for an interview with the judge during which she makes the admission that her husband is not actually the biological father of her son. Determined to be a troubled child by the authorities despite the fact that his criminal behavior is clearly a reaction to the even greater crimes of emotional and intellectual abandonment by his family and the school system, Antoine gets sent to a juvie center for observation.
The center turns out to be a school with even worse conditions for students than his old one, but he also gets to have long discussions with a psychologist who provides Antoine with his first opportunity to talk about his life and feelings with an adult who actually listens. His mother shows up one day with news that she and his stepfather were going to try to bring him back home, but a letter he sent to her husband informing him of her affair has caused so much discord that she instead has made the decision to disown and leave him to his own devices to survive.
Realizing there is no point in staying at the center with no hope of rejoining his family, he instead escape and starts running. He runs and runs and runs until he reaches a point at which there is no more place to run: the shoreline of the ocean. After aimlessly traipsing about in the shallow waters for a moment, he turns and stares directly into the camera where the film draws to a conclusion on a freeze-frame that zooms into his face.