After a high-ranking North Korean official requests asylum, KCIA Foreign Unit chief Park Pyong-ho and Domestic Unit chief Kim Jung-do are tasked with uncovering a North Korean spy, known as Donglim, who is deeply embedded within their agency. When the spy begins leaking top secret intel that could jeopardize national security, the two units are each assigned to investigate each other. The International Unit and The Domestic Unit of the Korean Spy Agency are tasked with the mission of uncovering a North Korean Spy known as Donglim who is deeply embedded within their agency.