Agathe and Regis have a little boy, Benoît, who is very capricious and sometimes aggressive. The couple, on the verge of divorce, is planning to go on vacation in order to better reflect on their decision. To do this, Agathe and Regis publish an ad in a newspaper: "Young couple seeks au pair grandmother to take care of little boy, 10 years old...". An old lady, Rose, shows up. She arrives with a fish and a bird she can't part with. The first contacts with Benoît are very unpleasant. Not discouraged, she realizes that he is unhappy and that he suffers a lot from feeling unloved in his family.
