Parisian everyman Antoine Doinel has married his sweetheart Christine Darbon, and the newlyweds have set up a cozy domestic life of selling flowers and giving violin lessons while Antoine fitfully works on his long-gestating novel. As Christine becomes pregnant with the couple's first child, Antoine finds himself enraptured with a young Japanese beauty. The complications change the course of their relationship forever.
The third in a series of films featuring François Truffaut's alter-ego, Antoine Doinel, the story resumes with Antoine being discharged from military service. His sweetheart Christine's father lands Antoine a job as a security guard, which he promptly loses. Stumbling into a position assisting a private detective, Antoine falls for his employers' seductive wife, Fabienne, and finds that he must choose between the older woman and Christine.
Recovering from an attempted suicide, a man is selected to participate in a time travel experiment that has only been tested on mice. A malfunction in the experiment causes the man to experience moments from his past in a random order.
Diego is one of the chiefs of the Spanish Communist Party. On his way from Madrid to Paris, he is arrested at the border for an ID check but manages to get free. When he arrives in Paris, he starts searching for one of his comrade to prevent him from going to Madrid where he could be arrested.
Professor Louis Delage is a kidney transplant specialist. He is so good in his field that his peers nickname him the "great man". But one day, one of his patients die during surgery and Delage starts doubting. Is he actually such a great man? To fight desperation he decides to take in the deceased child while devoting more time to Florence, his hitherto neglected wife.
The romantic life of the head of a bandit gang, wanted by the police. Cartouche gets away with being deported to Louisiana after unmasking a plot by a Duke against the throne.
Jacques Herbelin is the faithful husband of Louise and the proud father of Cécile, a kind little girl. But Louise does not reciprocate her husband's affection and prefers to cheat on him in the arms of Marquis de Condottier. The latter is a sinister character who, not satisfied with being Herbelin's wife's lover, sets his heart on their daughter, who has now become a pretty young lady. Jacques can't take it anymore.
