The story took place in the early days of the Republic of China. Liao Sicheng (Liu Xiaofeng) and Fang Tianyi (Zhang Ruoyi) were adopted by the wealthy businessman Gu Hansen. The two and Gu Hansen's biological daughter Gu Ting (Wu Ting) grew up. Essence After graduating from the Huangpu Military Academy, Liao Sicheng went to Japan for further studies. During this period, he met the beautiful Japanese women's Dajima Yumi (Zhang Wenqi). Essence On the other side, the brave and intelligent Fang Tianyi was loved and trusted by Dai Yan (Wu Xiubo). Dai Yan gave him the code of "black fox", hiding under this mask, Fang Tianyi and his colleague Yu Mei ( With the help of Li Man), as the Japanese and the traitors are fighting wisdom, in fact, like Yu Mei and Liao Sicheng, they are underground party members who belong to the Communist Party of China.