In nineteenth century China, two girls named Snow Flower (Gianna Jun) and Lily (Li Bing Bing) are forever bonded together as sworn sisters. They are paired as ''laotong'' by a matchmaker who is also responsible for arranging their marriages. They are isolated by their families and communicate by writing in a secret sisterly language, ''Nü shu'' (a historical practice in China in that period) on a unique Chinese fan that Snow Flower possesses.