Gu Yizhong (played by Zeng Shunxi), a child of the Gu family in Suzhou, returned to China after graduating from the Department of Architecture at the University of Pennsylvania. After the outbreak of the Anti-Japanese War, after a failed rescue operation to assist his girlfriend in the underground party, all the contact points of the Suzhou underground organization were exposed. Gu Yizhong was mistakenly believed to be a traitor in the party because of the deliberate frame-up by the Japanese puppets. Unable to prove his innocence, he took the initiative to sneak into the Japanese puppets. After several twists and turns, he finally became a latent member of our party in the Suzhou Special Agent Station. Gu Yizhong faced tremendous pressure and fought wits and courage with Zhou Zhifei (played by Zhang Songwen), the station chief of the Suzhou Special Agent Station, and Kondo Toshio, a Japanese military adviser. He took the opportunity to find out the real traitor "Black Eight" in the party and remove him. Gu Yizhong continued to secretly collect intelligence for our party, saved comrades in the party from danger many times, and provided great support and help for the anti-Japanese and national salvation movement of our party's Suzhou underground organization. He bravely moved forward with unswerving faith and continued to grow in the struggle.