It tells the story of the battle between Kuomintang and Communist agents for the physicist Tong Jiang Nan in Hong Kong In 1948, after the "May Day Slogan" was published, a group of patriotic democrats in Hong Kong, represented by Professor Tong Jiang Nan, actively responded to the call of the Communist Party and prepared to return to the liberated areas. The Kuomintang reactionaries obstructed and sabotaged this and sent Zhang Mu and others with the intention of controlling the professor and others. Su Xing was once a student of Professor Tong Jiang Nan. He received the task of the organization and went to Hong Kong to escort the democrats back to the liberated areas. He started fighting with the Kuomintang reactionaries in Hong Kong. A life-and-death battle.