Ten years after discovering her murdered uncle, Ena and Detective Hansaem must cooperate to stop a series of similar murders - each linked by strange puzzle pieces.

Detective Ma Seok-do changes his affiliation from the Geumcheon Police Station to the Metropolitan Investigation Team, in order to eradicate Japanese gangsters who enter Korea to commit heinous crimes.

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.

When the investigation of 'Koreagate' takes place, Park Yong-gak, a former KCIA director who knows everything about the government's operations, heads to the United States in exile.

Seonwoo Jung is an artist who claims “borrowing” rather than plagiarism when an old friend who’s been abroad re-enters, and agitates, her life: a secret meeting with a curator and her old friend suggests she seduce her partner.

Kwon Sang-Gon is a gangster who wants to have a cool life. He becomes a gang boss and expects to reap the rewards of the top position. Kwon Sang-Gon soon realizes his life is a living hell, filled with conspiracies and betrayals.

At some point, they dreamed of becoming a part of the national taekwondo team, but now, they have surrendered to reality. There were three friends, Hoon-i, Seong-ho, and Tae-yeong.