In the summer of 1939, in Shanghai under Japanese occupation, Wang Mutian and three or four boys of the same age of sixteen or seventeen were carrying out their naive anti-Japanese movement. Wang Mutian's sister's fiancé Hong Wangnan was an engineer of the Kuomintang Air Force. He secretly returned to Shanghai to network aircraft manufacturing talents and contributed to the manufacture of fighter jets for the Central Aircraft Manufacturing Plant. At the same time, Wang Mutian's cousin Sang Xia came to Shanghai from Singapore. In fact, this Sang Xia was an imposter. She was a member of the Communist Party. Her purpose was to open a channel for the New Fourth Army to purchase medicines and other materials from overseas. Under the guidance of Sang Xia, Wang Mutian gradually grew from an ignorant patriotic youth to a determined revolutionary fighter. During this time, these young people from the Wang family and the Hong family also experienced various trials and tribulations and embarked on different paths in life.