Kuen, a rookie cop who flunked every single important test as a cadet. However, Hong Kong needs cops so she graduates anyway. Sentenced to the Lost Property Department, Kuen can only gossip with her co-workers and lust after hunk cop Hung (Raymond Wong Ho-Yin).
However, Kuen gets her chance pretty quick. The Serious Crime Unit picks her for minor undercover work because she has no family, boyfriend or dog, and wouldn't be missed if the target decides to off her. She's assigned to bug suspected triad guy Hoi (Daniel Wu), but thanks to nutty situation comedy circumstances she ends up catching his eye. Hoi decides to pursue Kuen, and the Serious Crime Unit couldn't be happier. Led by Officer Chung (Hui Siu-Hung) and previously-mentioned hunk Hung, the cops go about setting up an elaborate cover for Kuen. They plan to keep her close to Hoi in hopes of discovering his evil plans.