It all begins very properly. Two nice married couples and their children go on a hot sumer weekend to a country house owned by an unmarried lady named Anna. But - as Mary Ann, aged eight, says -'Anna likes kids' parties because she like kids better then grownups. ' And somehow it is not long before these grownups seem to be getting younger; at first hesitantly, then with enthusiasm abandoning the conventions of adult behavious sliding ever deeper into a world of childish games and sudden passions and violent quarrels. As the practical Mary Ann and her dreamy, sensitive best friend Lolly watch this change they are at first excited, then puzzled, finally frightened and angry. Even Anna finds it hard to return to the adult world. As for the children, they have become - each in their own way - suddenly rather older; which is, as you choose, a comedy or a tragedy.