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.

'Geon-woo', brutally trampled by Daejinbuk High's best 'Sang-goo', vows revenge as he practices martial arts. After hearing about 'Geon-woo's comeback, 'Sang-goo' immediately starts to threaten and ask for bribes. To stop 'Sang-goo', they fight head-to-head. To determine who is the real 'best', the bloody fight begins!

Jo Dal-hwan plays Lee Ho-yeon, a salesman from a pharmaceutical company who is very people-shy.

Yong-gae is a rowdy gangster from Musan with no home, no background and nothing to lose. He's the loyal dog of Chairman Choi, his boss, and does even the dirtiest task he asks. One day he meets Soo-yeon, the daughter of a debtor. Yong-gae, who used to think being born in and dying in Musan wasn't so bad, falls for Soo-yeon and decides to leave Musan for the first time. However, Chairman Choi orders for him to be killed, and Yong-gae is provoked by his rival, Sang-cheol.

'Typhoon' made a name for fighting in middle school. He decided to forget the past and live a quiet life, but his resolve crumbles when he collides with school officials. Meanwhile, 'Sang-min', who stands at the forefront of the Iljin group and leads it, and 'Ik-jun', a gangster who controls it from behind. The 'Sang-min' gang and gangster senior 'Ik-jun' and gangster extort money by blackmailing male customers who want to use female students to have an aid relationship. 'Typhoon', who does not join the school Iljin, runs into conflicts with the Sangmin and gang, and the two of them are in a situation of improvisation...

Three nights before enlisting, Seung-wook decides to leave his mark since he can't avoid the military so he flirts with everyone. However, his school senior So-yoon nor his blind date Il-hong will fall for him. The night before he leaves for the army, Seung-wook decides he's going to see some action with the two girls. The project of 'leaving a mark' starts now.