I just remember there was a married guy who was leading a double life, he had a child with his mistress. When his wife found out she confronted the mistress during a rainy day on a steep hill near a busy road hitting her with a rock, probably killing her or just badly wounding her. I just remember the mistress rolled down the hill on the road and a guy got out of the car to help her.
The mistress and her child were poor and living in a small apartment while the wife was classy and well off. Not sure if the cheating husband was a detective or that was another guy, maybe the one who stopped his car to help the wounded woman. That is all I’ve got.