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 flight scheduled to leave Incheon International Airport for New York makes an emergency landing at Gimhae Airport due to engine problems. As the passengers will take an alternative flight the following day, they are staying at a hotel provided by the airline during a layover. While staying an unscheduled night at the same hotel, they have an unexpected experience.

Young-jin doesn't get a chance to get a promotion because she is a woman. On the other hand, Jun-seul easily gets a job as a manager with the power of connections.

Jay, a promising young writer, is about to publish her new book. Geonwoo, Jay′s roommate and lover, works as an English instructor at a private institute and silently assists Jay. Both of them care about each other and are happy as they are. However, Jay’s unplanned pregnancy brings huge changes, causing conflicts between the two.

Kyung-hak, who has been studying to become a police officer, is forced to pay back his mother’s debt of $20,000. Already struggling and having to work part- time while studying, Kyung-hak is now forced to make big monthly loan payments on top. Eventually, Kyung-hak stops studying and becomes a deliveryman to make ends meet. Meanwhile, cracks start to form in his relationship with his beloved girlfriend Hye-jin.

Suna, Jisu, and Bomi, who contain different stories, get into a car accident on a last-minute trip to visit the graveyard of Jisu’s parents. The three spend the night in an unfamiliar place and learn about each other’s secrets.

Oh-seong is a son of an illegal Mogolian immigrant, and a member of a wrestling team in Nam-cheon high school. He wishes to compete in the National Sports Festival but it is impossible for a stateless person. Oh-seong’s mother, Nyamka, is living with a man named Yeong-cheol who had promised to marry her long ago, but it seems Yeong-cheol won’t keep his words. An unexpected opportunity comes to disheartened Oh-seong, but he gets involved in a serious incident.