Once part of Korea's top-secret National Intelligence Service, a group of talented female agents is reassigned to go undercover in a case involving corruption and leaked trade secrets at the country's largest conglomerate. After several mistakes during important missions, Chan Mi was reassigned to the cybersecurity team but dreamed of returning to her former role. Mi Soon has left agent life behind and become a full-time homemaker. Meanwhile, Ye Eun, a smart, single mom and desk agent, dreams of being promoted to an undercover spymaster working in the field. Their lives collide when Kwan Soo, a longtime director in the NIS, recruits all three for a do-or-die mission.