In June 1970, Shen Mengyao, a literature major from the modern era, transmigrates into the body of a military wife with the same name who is traveling by train to Xiangcheng. The original owner had attempted suicide due to depression caused by village gossip after her husband, Xiao Ye, abandoned her on their wedding day for an urgent military mission. Upon waking, Shen Mengyao finds herself held hostage by a bandit named Er Gouzi. Instead of panicking, she uses psychological tactics to lower the bandit's guard, then physically overpowers him with surprising strength, allowing Xiao Ye to arrest the criminal. During the incident, she also encounters Liu Xiaolong, a man she saved from drowning in her past life, who is traveling to visit relatives.
After securing the bandit, Shen Mengyao suffers a seizure and binds with a system named Xiaobai, which offers rewards for completing tasks related to mechanical weapon development. She discovers she has transmigrated into a novel as a cannon fodder supporting character destined to die in the hostage situation. Realizing the plot, she urges Xiao Ye to interrogate the criminal to prevent his original fate. Shortly after, she identifies a spy on the train who dropped a mission note containing instructions to infiltrate a military factory and steal a cowhide map. She captures the spy by feigning a mental breakdown and physically assaulting him, handing him over to military intelligence.
Upon arriving at the military base, Shen Mengyao and Xiao Ye check into a guesthouse. There, she confronts a harassive employee, Liu Hongying, who attempts to assault her in the bathhouse. Shen Mengyao defends herself, exposes the woman's misconduct, and forces her to pay fifty yuan in compensation. Meanwhile, the captured spy reveals that Er Gouzi possesses a cowhide map linked to a secret gold mine and spy network in Shenjia Village, Shen Mengyao's hometown. The military interrogates Er Gouzi, who provides the map, leading to a broader investigation into espionage activities targeting local military factories.
Xiao Ye, seeking to make amends for leaving Shen Mengyao on their wedding day, provides her with his bankbook containing three thousand yuan in savings and applies for family housing. Their relationship begins to warm as Shen Mengyao appreciates his sincerity and financial generosity. She plans to use her system rewards and future earnings to support her impoverished cousin, Shen Hongmei, who had previously helped her aunt. The story establishes Shen Mengyao's determination to navigate this dangerous era using her modern knowledge and system abilities, while Xiao Ye works to protect her and uncover the spy ring threatening their country.
