On the eve of the victory of the Anti-Japanese War, Ou Xiaoan, an underground party member lurking in the military command, successfully escaped from the prison of the Japanese Army's Biochemical Gas Research Institute. He was seriously injured and fell into coma on the way. He was discovered and rescued by the Chinese Expeditionary Force.After waking up, Ou Xiaoan found that he had lost the memory of nearly four years in prison.Ou Xiaoan started from the end of his memory four years ago, picked up scattered memories, secretly investigated and intended to expose the criminal face of Japanese spy Li Shaotang.During this period, he and Qin Moqing, an underground party member, went from questioning and testing each other to jointly working together to find the Japanese Army's Biochemical and Poison Gas Research Institute and captured the Japanese Army's Intelligence Commander Ohashi Kazano.After the victory of the Anti-Japanese War, the Kuomintang prepared to take over all the people, property and materials left over from the Japanese Army's Biochemical and Poison Gas Research Institute to prepare for future operations.Ou Xiaoan learned this information and smashed this vicious plan. At the same time, he revealed the true face of Li Shaotang as a Japanese spy. Ou Xiaoan, codenamed “Lone Star” in the underground party, finally returned to the embrace of the party organization.