After her older sister was driven to death by a wealthy elite trio, Gu Zhaoning does not plan to let a single one of them go. Disguising herself as Lu Chengxiao's girlfriend, she smilingly infiltrates that game: outwardly meek and yielding, inwardly provoking, recording, and gathering evidence. Using gentleness as a knife, she feeds the suspicions among the three of them, watching them turn on each other like dogs biting dogs. She never dirties her hands, borrowing only their blades. By the time the wealthy family realizes, the inescapable net has long been spread; evidence, testimonies, and public opinion have all fallen into the trap, and the three killers are finally sentenced to life imprisonment. Putting down the verdict, she turns around and boards a plane to see the world for her sister.