Told in nonlinear fashion, with frequent flashbacks to the four previous films, it stars Jean-Pierre Léaud, Marie-France Pisier, Claude Jade, Dani and Dorothée.

One day, as Antoine and Christine are leaving the courthouse after finalising their divorce, he is spotted by an ex-girlfriend of his, defense lawyer Colette.

At the Gare de Lyon, Colette boards a train bound for Aix-en-Provence, where she is due for a court case.

Antoine is at the same station to drop off Alphonse, who is leaving for a summer music camp on a train on the opposite platform.

Antoine calls Sabine from a phone booth to inform her that he will not be able to accompany her to her friend's party that night, as he had forgotten about Alphonse's trip.

Pretending to be discussing a new novel he has been writing, Antoine reveals how he met Sabine: some time before, in a phone booth, a man destroyed a picture of her, his former lover.

Antoine visits Sabine and apologises for hanging up on her, but having tired of his inattentiveness, she angrily gives him back the letters he has written to her.

Realising that she must tell Xavier that she loves him, Colette gives Sabine's photo to Christine and leaves to reunite with him at the bookstore, where they kiss.