The Lesson of Courage - Chinese drama short film

The story happened in a small town in the south of China,On the way home from a junior high school, Xiao Nan passed the mountain road and see a shack. He witnessed his drunken mother is being raped by a homeless in the shack. After the incident, Xiao Nan's mother tries to keep that secret from the shack, in order to keep her promotion. However, this secret is slowly building a black hole…