Set in 1953, spies plan to set off a explosion on the National Day.

During the War of Resistance Against Japan, a CCP army unit guarding the southwest border follows what is ostensibly a trading caravan and discovers that these traders are actually smuggling arms and spy equipment to Chiang Kai-shek and his American allies.

During the civil war, the counterintelligence agencies of the Chinese People's Liberation Army fought against Kuomintang spies and saboteurs. Battles are already taking place in the suburbs of the city. Zhang Go-zhong, head of Kuomintang intelligence, following orders from his command, leaves a large group of saboteurs in the city. He hands over the lists of this sabotage group to the remaining resident, the major merchant Cui Xizheng. The PLA enters the city and establishes people's power. But the hidden enemy immediately begins to act.