Lynn (Shu Qi) is a professional assassin, hacker and espionage specialist. While her shyer sister, Sue, handles the computer aspects of missions at home, Lynn takes on all the dangerous tasks. Sue resents Lynn for underestimating her, though Lynn is just trying to protect her younger sister. Police detective Hong (Karen Mok) pursues the two after they successfully kill the chairman of a major company, but all three must work together when a common enemy wants them dead.