Eva Huang (Kung Fu Hustle) is Xiao Ling, a super-cute ninja who works with her master (Eddy Ko) to protect a street musician named Copy. Evil mastermind Brian suspects that Copy holds the key to opening a mysterious red box that contains Jinrui, which is said to cure any disease known to man. Brian intends to use Jinrui to manufacture a cure-all drug and make a ton of dough on the market, and enlists an army of ninjas to aid him. Xiao Ling wants Copy alive, but fellow ninja Hibiki is willing to kill Copy to keep the secret safe.  The two female ninjas find themselves at odds, but when Brian's ninjas snatch Copy, the two must join forces.  Can Xiao Ling and Hibiki use their deadly ninja arts to save Copy and prevent Jinrui from falling into enemy hands?