A depressed, obese woman tries to lose weight in order to win back her ex-boyfriend with the help of a fellow Hong Konger whom she met in Japan.
Although she hopes to follow in her father's footsteps as a master constable, Luk Sap-Yee is an impulsive and idealistic constable whose skill and competence are often dismissed by her corrupt male peers. When Sui Tong-Lau, the newly appointed magistrate, arrives in Sap-Yee's city, they wind up working together to solve a number of unusual cases.
