In 1943 Shanghai, an explosion leads to a showdown between Communist undercover agent Lu Zhengyang and former police officer Lin Shaobai. Six years later, Lu Zhengyang, now a key member of the Shanghai Public Security Bureau, recruits Lin Shaobai, the "Shanghai Expert," to tackle major cases and thwart the plots of veteran spy Zheng Lanting. As they work together, Lu Zhengyang and Lin Shaobai build trust and become close comrades.
In 2002, newly graduated An Yan was assigned to teach at Heping Middle School in Changzhi County. Initially struggling with the rural school's environment, she eventually embraced the value of rural education and became a respected teacher. Throughout her journey, she worked to implement key programs and improve the educational environment for local children.