Birdhouse (1970)

14 year old Hannah is reluctantly taking part on family weekend at her mothers friend Sally. When they arrive to a welsh lake, Sally can clearly see that Hannah cannot stand her stepfather Andreas and is even accusing him of killing her dog. Andreas is certain that there is something wrong with the girl and hopes that Sally will convince her insecure mother to take action on her. While the adults talk, Hannah wanders deeper in to the woods where she finds a dangerous new friend.