A Dangerous Woman, starring Debra Winger, is about a woman with some sort of developmental disability (that is never specified). She lives in her young aunt's guest cottage and works at a dry cleaners in a small town. She has great difficulty interacting with others and has frequent outbursts. She is also the subject of abuse and cruelty and injustice. Because she is often ignored, she observes a lot around her and is aware of others' secrets.
The drama begins when she gets fired for stealing from the register at work -- she didn't do it and she knows who did. She becomes obsessed with wanting her friend from work to believe her. At the same time she develops a tender relationship with a carpenter her aunt hires. The relationships all explode, in a pretty awful way, but the resolution is satisfying.