Ji Sung, an NIS agent, and Do Kyung, the new operation manager, get arrested for a drug case at the airport.
An emergency occurs at Incheon Airport due to Wang Wei, and Ji Sung embarks on a fierce chase to catch him.
The industrial spy causes the security level to be raised, and Ji Sung finds a lead for the spy case.
While chasing down Charlie, Do Kyung is held hostage and Ji Sung rushes to save her.
Myung Woo asks Ji Sung for help, but is refused. Do Kyung sees Yi Kyung, but turns away and leaves.
During the runway closure, Do Kyung notices her feelings toward Ji Sung, but feels hesitant due to his ex.