Madness of Two (1982)

Set a on a lighthouse on a remote island the film tells the story of Molly Domino and her dependence on her husband Michael who, with children Eve and Peter, complete her world. Their utopia is interrupted only by monthly visits from handsome young helicopter pilot, Dan, who brings them essential supplies plus the occasional gift. Dan's visits fan the flames of the emerging womanhood of their adolescent daughter, Eve, simultaneously, provoking the father's religious fanaticism. Story is based on a study of the psychiatric condition known as Folie A Deux, the psychosis of association.