The Hong Kong Airport Special Police Unit (ASU) is a special police force responsible for maintaining public and aviation security, counter-terrorism, key personnel protection, disaster support and many other areas. Encountering different situations on duty, they see the joys and sorrow of life that make them reflect on their own lives. With every step forward, they establish a sense of mission as the airport security police.
The forensics team and the crime team on Hong Kong's police force are challenged once again as the squad is staffed with new personnel. This time, the crime-solving police force led by Go Sir, Dr. Man, and King Sir, who all work together with their respective teams to solve murder mysteries.