Antoine Doinel, now a young man, is discharged from the army as unfit because he prefers reading novels and writing to his violinist sweetheart, Christine Darbon, rather than following orders. He has filled Christine’s mailbox with lengthy letters from military days, some of them sharp in tone, and she never replies. Their separation frames a quiet, stubborn determination in him to hold onto his own passions even as life pushes him in new directions.
Christine is away skiing with friends when Antoine arrives at her family home, and her parents take on the task of entertaining him. They are glad to see him and, recognizing that he needs a job, help him land a position as a night clerk at the Hôtel Alsina, a quiet place where Antoine spends most of his time lost in books. Christine eventually comes to visit, and after such a long separation, the two seem to rediscover the spark that once drew them together.
One morning, a man accompanied by a private detective brings Antoine to a room where a wife has checked in and is sharing a bed with another man. The husband explodes in anger, the room is torn apart, and Antoine bears the blame, losing his job in the process. In a twist of fortune, he later befriends the detective and finds work at the man’s agency.
At the agency, Antoine’s education in the subtleties of investigation begins to take shape. While following a subject one day, he unexpectedly crosses paths with Colette, the object of his earlier infatuation who is now married to Albert Tazzi and has a child. The demanding nature of the work—balancing attention to Christine with the shadowing of others—soon strains his relationship with Christine. Then Georges Tabard, the bumbling shoe-store owner, visits the agency seeking help to understand why he is disliked. Although Georges has never worked in a store and is clumsy, Antoine poses as a stock boy to solve the mystery, and in the process he falls for Georges’s wife, Fabienne, who seduces him. Overwhelmed by the tangled loves, Antoine breaks up with Christine, telling her that he has never “admired” her.
The agency grows tense as it becomes clear Fabienne might be cheating on their client, and Antoine is forced to confess the truth. That same day, his detective mentor dies, leaving him with a heavy sense of loss and a new sense of responsibility.
Antoine’s trajectory then takes a sharp turn into ordinary labor as he becomes a TV repairman, trying to steer clear of Christine. A reckless driving episode results in a minor crash with Christine’s father’s car, but no one is hurt, and her father forgives him. To win her back, Christine deliberately disables her TV and summons Antoine’s company to repair it, spending hours watching him struggle to fix a tube-less set. Seizing the opportunity, Christine reconciles with Antoine, and they consummate their renewed relationship. The morning after, without a word, Antoine proposes, and Christine accepts.
As they stroll through a park together, a man who has trailed Christine for days approaches and declares his love, describing it as “permanent” and contrasting it with the “temporary” love of others. When he leaves, Christine assumes the man is sane, or perhaps not; Antoine, recognizing a reflection of his own erratic patterns, quietly concedes, “He must be.”
> He must be.
