Bank manager Yu Puyuan employed a private detective Wu Feng to collect evidence of adultery by his wife Zhang Xiujuan. Despite tedious efforts Wu could find nothing. His suspicions grew rapidly as Yu pressured him to present the material. He tried to probe further but Yu gave him no clue.

Meanwhile, Zhang was annoyed of being traced by Wu. One day, Zhang went to visit a friend Zhao Manli where she also met Wu. Zhang pretended that she had never known Wu, and picked up his keys dropped to the floor when Wu was speaking to Zhao. She left quietly for Wu's house to find out who he was. Not until he arrived home did Wu recognise his keys were lost. He was even more astonished to see Zhang sitting in the room waiting for him. Knowing that Wu was a detective Zhang wanted to seek his help. As the daughter of a bank manager, she was in love with a teacher and was pregnant. While her father was angry at her pregnancy, Yu, her mother's brother, forced her to marry. Soon Zhang's father died, leaving a will under which Zhang and her baby would inherited his wealth. Furious at the decision, Yu kidnapped Zhang's child and forced her to sign an agreement, by which all her wealth should be kept in Yu's custody, and if they divorced, all her property would become Yu's. Wu gave Zhang his deepest sympathy and was determined to help her.

Yu had embezzled the bank's funds for his smuggling business and was eager to leave Hong Kong, but still wanted to engulf the property of Zhang's before departure. This was why he was so eager to ask Wu for evidence so that he could divorce Zhang. Wu's failure to produce the evidence prompted Yu to ask Wu to pretend to be Zhang's lover, so that his assistant could take pictures of them together. Wu agreed but always arranged Zhang leave the scene before Yu and his men could take any action. Knowing that his senior Lin Daxiong found that Yu was involved in smuggling, Wu tried to bribe Yu's man Qian Laosan to steal the agreement signed by Zhang but failed. He was locked up instead. As Yu was trying to threaten Zhang to sign the divorce documents, Wu passed a secret message to Lin and urged him to report the police. As Zhang and Doctor Zhou, who was fully aware of the developments, arrived, Doctor Zhou managed to stir up conflicts between Yu and Qian. Soon the police arrived and apprehended Yu and his men.

Starring: Zhang Xiujuan - Lin Dai Wu Feng - Yan Jun Yu Puyuan - Luo Wei Qian Laosan - Jiang Guangchao Doctor Zhou - Jiang Nan