Just The Three of Us.

1970s, six-and-a-half-year-old Sébastien is a sensitive, highly imaginative child. Despite the affection he feels for his father, a dreamy inventor, he notices his mother's loneliness and how there is a lack of love in her life. When they move the house, it won't be long before he sees in Philippe, his new neighbor, an ideal Prince Charming for his mother.