Policeman No. 223 (Takeshi Kaneshiro) suffers from lovelorn syndrome after a breakup. After a brush with a blonde female killer (Lin Qingxia) and a strange encounter and a night of tenderness, he unexpectedly welcomes a brief warmth of heart, even though he originally thought that everything, including "love", has a shelf life. However, their love is over. A new waitress at a fast food restaurant, A Fei (Faye Wong), falls in love with policeman No. 663 (Tony Leung), who often visits the fast food restaurant. After opening the "breakup" letter left by his girlfriend (Zhou Jialing) at the fast food restaurant, A Fei knows his mood, steals his key, sneaks into his house when he is not at home, and quietly changes his life while sleepwalking. Finally, when he sees her, he feels the return of his emotions. However, this is just the beginning of their love.