When Panisse dies of old age, his last wish is for 20 year old Césariot to learn about his true parentage. So the boy visits his real father, who fixes cars in Toulon, but he does so under an assumed name.
Marius has gone to sea and left Fanny, who turns out to be pregnant. When Panisse still remains willing to marry her, she accepts in order to safe face.
Fanny tries to make Marius jealous by flirting with the much older Panisse. Although Marius admits he has strong feelings for her, his first love is the sea.