Before the victory of the War of Resistance against Japan, Yu Zecheng, a KMT intelligence officer, was developed as our underground worker due to his discontent with the corruption of the Kuomintang. He was stationed in the Tianjin branch of the Military Intelligence Bureau and given the code name "Emei Peak". For work needs, he pretended to be a couple with Cui Ping, the female guerrilla captain. Cui Ping's maladjustment to being an official's wife led to dangerous situations one after another. Also, Yu Zecheng's lover Zuo Lan arrived in Tianjin to carry out tasks and was suspected by the secret agents. Yu Zecheng, Zuo Lan and others jointly got rid of and drove away Ma Kui and Lu Qiaoshan from the Tianjin station, completing their undercover mission. Zuo Lan's sacrifice made Cui Ping understand the importance of the covert struggle. Her cooperation with Yu Zecheng became more tacit. They obtained the city defense plan of Tianjin. But a fatal mistake let Cui Ping flee everywhere. On the eve of liberation, Yu Zecheng went through great efforts to obtain the list of the Kuomintang undercover agents but couldn't send it out. On the way to the airport, he discovered Cui Ping and handed over the list to her. Since then, they parted ways and Yu Zecheng continued to carry out his undercover mission......