Julie Christie stars in this adaptation of the classic novel by L.P. Hartley. A young teenage boy, Leo (Dominic Guard), is invited to a wealthy school friend's family estate and is drawn into a love affair between his friend's twenty-something sister, Marian (Christie), and the family neighbour, even though she is engaged to be married. She uses Leo as a go-between, sending messages to her lover. Despite feeling he is betraying her fiancé Hugh (Edward Fox), Leo carries on being the go-between and discovers more about the attraction between men and women along the way.