A painful but exciting story of Oh Soo-jae, a cold lawyer who has become empty while pursuing only success, and Gong Chan, a law school student who is not afraid of anything to protect her.

The story of a huge incident faced by Seo Soo-yeon from the support management team that supports and manages NIS field agents in China, Jang Cheon-woo, a hidden NIS black agent and Do Jin-sook, deputy director of overseas parts.

A Korean-style spy investigation show with a story about a top National Intelligence Service (NIS) agent. In his endeavor to uncover the internal traitor that brought him to his downfall, he confronts a much bigger enemy behind the organization. Han Ji Hyuk is the top field agent in the NIS. He is held in awe by his colleagues for his perfect record and skill at completing missions. He had been driving an organized crime syndicate into a corner when he vanished off the face of the earth, but he returns a year later to shake up the syndicate once more. Seo Soo Yeon is the head of team 4 of the Crime Information Center who is excellent at performing her duties and solving cases. She has great affection for people, and she especially cares for her teammates.

An unfathomable incident introduces a genius engineer to dangerous secrets of the world — and to a woman from the future who's come looking for him.