A tenacious investigator goes undercover at a securities firm to expose corruption, but her mission is complicated by its new CEO — her former lover.

Won-cheol of the National Intelligence Service of the Republic of Korea is offered a mission. Eliminating VIPs who participated in the operation to develop weapons of mass destruction in North Korea. Won-cheol is forced to accept the mission while thinking of her daughter 'Ah-reum' who is in danger - The secret operation of South and North Korean special agents begin.