Song SeungHyun(FTIsland) is a young, yet experienced assassin that kills for a living. He and his partner, Jang HyunSeung(B2ST), have never had problems with their jobs until this mission came along. Kill Lee SunKyu( SNSD sunny). What will happen if SeungHyun actually bonds with the girl he is meant to kill, as well as her handsome cousin Lee HongKi? More importantly, what will his partner think of all of this?