Giới thiệu: After the announcement of the May Day Slogan in 1948, a group of patriotic Democrats in Hong Kong, represented by Professor Tong Jiangnan, responded actively to the call of the Communist Party and prepared to return to the liberated areas. The Kuomintang reactionaries obstructed and destroyed it, and sent Zhang Mu and others to control the professor and his partners. Su Hang was once a student of Professor Tong Jiangnan, received the task from the organization, went to Hong Kong to escort democracy activists back to the liberated areas, and launched a life-and-death contest with the Kuomintang reactionaries in Hong Kong. As soon as Su Hang arrived in Hong Kong, the enemy killed Tu Zhe, the deputy editor of Ta Kung Pao who was responsible for contacting Professor Tong, which caused great difficulties to his work. To escort Professor Tong and others back to the liberated areas as soon as possible, Su Hang started by tracing the murderer who killed Tu Zhe, dug out Zhang Mu's direct contact Dang Xunqi, found the hidden enemy "Bee", stopped Zhang Mu's plan to leave Hong Kong with Professor Tong, and rescued Professor Tong and his daughter Tong Sheng kidnapped by Zhang Mu. On the ship sailing to Yantai, he completely overpowered Zhang Mu who wanted to blow up the ship, and successfully escorted democracy activists safely back to the liberated areas.