Annie's Garden (1997)

In front of his 15-year-old son, a father loses his temper and strikes his younger daughter, thinking she's trying to run away from him. Jump ahead ten years: the dad is dead, the mom is gone, and the son, Luke, is raising his now grown sister, Annie. He's overprotective, and she seems blood simple, a coquette and an innocent. He runs the diner in town, and one day, Lisa, a callow writer-to-be, comes through from Manhattan, keeping a journal, looking for interesting people. She takes a shine to Annie and then to the muscular and well-read Luke. But what is their secret, how many of the townsfolk are in on it, and what will Lisa do when it all becomes clear?