In Jinjiang City, the head of the Major Crime Investigation Unit, Fan Guangtian, leads two capable officers, Jiang Husheng and Li Yun, in a battle of wits and courage against criminals. The Jiang family is one of the prominent households in Jinjiang. After graduating from the police academy, he returned to Jinjiang City to take care of his grandma. Li Yun is two years junior to Jiang Husheng, and has a tomboy character since childhood. In the police station, she dated Zhaogang, a colleague in the detective team and also Jiang Husheng's good partner. Just as the two were about to get married, Zhaogang sacrificed himself in a capture operation to protect Jiang Husheng while the criminal escaped. To avenge Zhaogang, Li Yun transferred from internal affairs to the detective team. Jiang Husheng took special care of her, and the two became a bickering couple. Three years have passed, the murderer who killed Zhaogang was finally captured by the two. Looking back, the two found that they had become the best partners for each other.