In 1999, before Macau returned to China, Macau police officer Ma Zhencheng (Chapman To) was suspended for getting into trouble, and his police career was about to end. Ma Zhencheng and his buddy were still going out at night, and they accidentally ran into a mysterious girl, Zhang Bixin (Isabella Leong). Zhang Bixin followed Ma Zhencheng home. Ma Zhencheng, who woke up drunk, thought he had a one-night stand with her. In addition, Bixin claimed that she was his daughter born after breaking up with his first love, which made Ma Zhencheng even more shocked. Bixin was homeless because she owed rent for several months, and her beloved dog Isabella was also driven away by the unscrupulous landlord and her whereabouts were unknown. As a father, Ma Zhencheng hoped to make up for his past responsibilities. Later, Bixin insisted on living with Ma Zhencheng, which changed the life of Ma Zhencheng, who had always been bohemian. In order to protect himself, Ma Zhencheng tried to take risks to get himself out of the crime, and his good friend Du Sir (Anthony Wong) also repeatedly persuaded him to no avail. Zhang Bixin was excited and prepared to marry her father, and she couldn't hide her pride in front of the boys in the same school. However, Ma Zhencheng gradually realized what responsibility was from Zhang Bixin.