The Villainess

Sook-Hee, a 7-year-old girl, witnesses her father's death but does not get a look at the killer's face; she only hears a whistled tune. Jang-Chun, a former friend of her father's who was jealous of a stolen jewel that her father had acquired, is present during the murder and finds the hiding Sook-hee. He kidnaps her and eventually sells her to a child prostitution ring. She is about to be assaulted by a client when assassin Lee Joong-sang saves her. Joong-sang kills the client, and she kills a henchman in the door just before the latter can shoot Joong-sang. Joong-sang takes Sook-hee with him and trains her to be an assassin.