In 1945, as the War of Resistance Against Japan comes to an end, the Japanese army secretly transports a large quantity of poison gas bombs to China. Ou Xiao’an, the ace special agent of the military, is injured while escaping from the “810” poison gas research institute. He is inadvertently rescued by Tan Moqing, another agent. When he wakes up, he discovers that he has lost nearly four years of memory. As they work together to expose the Japanese conspiracy, Ou Xiao’an and Tan Moqing frequently join forces, ultimately unveiling the identities of the Japanese spies while also revealing their own roles as underground party members. However, a greater crisis looms ahead; they remain unaware of the whereabouts of the “810” research data and the hidden gas bombs. Faced with numerous dangers and obstacles, how should this group of lonely yet brave individuals advance and fight courageously?