A ten-year-old daughter of a general meets and helps a travelling monk, who decides to take the girl on as an apprentice. Denied permission to do so by the girl's father, the monk kidnaps her and begins to train her in assassination and using multiple dimensions to move undetected. The girl is determined to become powerful enough under training to steal back her own life, and learns fast with the help of her two 'sisters', other girls taken and trained by the monk. The monk names her Yinniang, or 'Hidden Girl'. To graduate into a full-blown assassin, Hidden Girl is charged with killing a general. She is detected by him, and they begin a discussion, during which she sees that he is a good man whose death will lead to a great loss of innocent lives. She refuses to assassinate him, and so the monk sends both sisters to do the job, but Hidden Girl uses her wits and training to defeat each of them in turn. Now free, she resolves to forget about returning to her small cloistered life with her father. Instead, she will use her abilities to 'steal' back the lives of others, and make the world a better and more peaceful place.