Lin Qiang is a project manager of a construction company and a full-time dad to his seven-year-old daughter. His wife Su Yao is a middle school teacher, and the family of three lives a peaceful and warm life. An anonymous letter breaks the tranquility, claiming that Su Yao is having an affair. Lin Qiang was suspicious and secretly investigated but found that his wife was doing something strange. He followed her to a remote community and saw her meeting a strange man. He resisted the urge to continue the investigation and accidentally uncovered the secrets of a criminal gang. In order to protect his family, he took risks and went undercover, surrounded by dangers. In the end, with the help of the police, the major case was solved and the couple reconciled. The truth was revealed. It turned out that Su Yao was an undercover teacher cooperating with the police. The family joins hands to return to an ordinary and happy life.
