In the early years of the Republic of China, Chief Inspector Xu (played by Zhang Guoqiang) formed an indissoluble bond with Jing (played by Jiang Zhiguang) of a foreign company because of a case, and each of them was given an oil painting to commemorate their meritorious service in solving the case that day. Many years later, the descendants of Chief Inspector Xu are still proud to join the police force. Xu Xiaoli (played by Yang Yi), known as the sharp sister, is a capable member of the police force. After joining the serious crime team, Xu Xiaoli followed her boss Lu Tianheng (played by Ma Guoming) to solve one difficult case after another. The one who assisted them with professional physics knowledge was Lu Tianheng's schoolmate, who was also an associate professor at the university and a descendant of the Jing family, Jingbo (played by Lin Feng). Xu Xiaoli, who was born in a humble family, gradually turned her admiration for Jingbo into love, and Jingbo also became more and more attracted to Xu Xiaoli who cared about him. However, due to the disparity in family background between the two families, Jingbo decided to give up this relationship due to his parents' obstruction. On the other hand, playboy Lu Tianheng and his close friend Minjia (played by Liao Bier) have always maintained an ambiguous relationship as both friends and lovers. However, unexpectedly, Minjia suddenly has a lover and wants to marry him. With the endless stream of anxious cases, how will the love of these two young couples continue...