If the Wind Frightens You (1960)

Claude (Elisabeth Dulac) and Pierre (Guy Lesire) are brother and sister, both at their 20s yet it is apparent early on that they are physically attracted to each other. Pierre, the eldest, feels guilty, but he can not prevent this attraction. And Claude, is she so innocent? This summer they spend their camping holidays in the dunes of the North Sea. In order to suborn their feelings they enter into relationships with others but nothing they do seems to work -they are always drawn back to their same fatal attraction.