This is a story about the Hong Kong Customs. Through the senior supervisor of the Copyright and Trademark Investigation Division, Hoi Fung (played by Benjamin Yuen), the chief trade control officer of the Trade Controls Division, Kwan Pui-yan (played by Mandy Wong), and the supervisor of the Customs Narcotics Investigation Division, Wan Chi-kei (played by Vivian Wong), the three led a group of elites and young newcomers of the Customs, including trainee inspector Chan Ka-hing (played by Chan Ka-lok), from egg tubes to atomic bombs, from milk powder tubes to white powder, by sea, land and air, all-weather, showing the new face of the smart customs. This group of people, in their own adversity, can also overcome difficulties, adhering to the purpose of "protecting the law, guarding the gate, and professionally taking responsibility", and contributing to the stability and prosperity of the local society. They are the "gatekeepers" that Hong Kong people are proud of.