Before the breakout of the Sino-Japanese War, Hong, Wang, and Peng were best friends. Hong and Wang secretly joined the local guerrillas after the Japanese began invading China. Hong ran a small business and Wang worked as a courier for a Japanese trading firm, hiding their true identities in order to collect intelligence on the Japanese for the Eight Route Army, and established a railway guerrilla unit. Wang soon found out that the trading firm he was working for was indeed an intelligence unit of the Japanese. They infiltrated the Japanese special forces and eliminated many Japanese. Suspicions arise from the Japanese as to the real identity of the individuals suspected of being part of the railway guerrilla forces, so called Flying Tigers unit, so the Japanese began to form a counter-spying operation and other under-handed means by recruiting Chinese traitors to uncover and eliminate them all.