In 1936, nine-year-old Mary Ann Hubbard (Miranda Fenn) and Lolly Zimmern (Lorin Jones), along with Lolly’s teenaged half-brother Leonard, spend a Fourth of July in the country with their parents and a teacher. The parents flirt and contemplate adultery while the children learn what they can about themselves and the world.
(Wikipedia)

Children have often remarkable insights into adult relationships. Good reading !