Tong Siu-wah is jobless. Tong shares a room with Chi-on. His neighbour Lai-ping is a factory worker. Another neighbour Siu-kuen is Manager Chin's mistress-to-be. Siu-wah never bumps into them. Siu-kuen is forced to be a mistress to pay back her family debts. Chin is about to marry Siu-kuen as his mistress. Lai-ping and Siu-kuen are friends and Lai-ping wants to help her. Lai-ping and Siu-wah have never met and they argue. Lai-ping separates their rooms, Siu-wah's glass frame was accidentally shattered by Lai-ping. Lai-ping meets her penpal and find out that Siu-wah him. They teach each other to trick their flatmates. Lai-ping puts a fake snake in his room. Siu-wah puts pins on her bed. The two eventually realized who each other is. Lai-ping helps Siu-kuen pay off her debt and not marry Manager Chin. Chi-on discovers that his boss' husband is Siu-kuen's husband-to-be. Chi-on reveals the truth to Mrs. Chin. Chin cancels the marriage. Lai-ping and Siu-wah become a couple.