During the Songhu War in 1932, a Japanese spy under the pseudonym Tao Lan planned to destroy the underground party group of the Communist Party of China and purge the Shanghai gang Paihui that helped the anti-Japanese war. Shen Fang, an underground party member lurking in Paihui, escaped death and contacted the new party organization Fenghuo Group to investigate the truth of the attack on the former party group and Paihui. Later, due to the need for struggle, he left Paihui and joined the enemy spy. He was misunderstood by his wife Hong Jiner who pursued progress, and Paihui split. In 1936, Tao Lan pretended to be an underground party member and sneaked back to Shanghai. He colluded with Yuanjie, his minion planted in the Kuomintang secret service, and won over Paihui to frame Shen Fang, confuse the Fenghuo Group, and implement the Canglong Plan aimed at destroying the anti-Japanese war and intensifying the contradictions between the Kuomintang and the Communist Party. Shen Fang cooperated with Fenghuo to confuse the anti-communist forces of the Kuomintang, actively guide Hong Jiner, win over the Paihui elder Changshu and the Kuomintang agents Zhou Yifan and Chen Baiyu who advocated anti-Japanese, cracked and smashed the Canglong Plan, and thoroughly settled accounts with Tao Lan and Yuanjie. He made great sacrifices, won the victory, united the anti-Japanese forces, and joined the national anti-Japanese torrent.