Kwon Do Hoon is an expert sniper and a secret agent working for the National Intelligence Service. To conceal his true identity, he lives a double life as a regular trading company employee, keeping even his wife Kang Yoo Ra in the dark. Though he is occupied with his work, Kwon Do Hoon cherishes his wife deeply. Meanwhile, Kang Yoo Ra, a dedicated homemaker, harbors a secret. Their tranquil existence is thrown into turmoil when Tae Koo emerges, posing a threat to their carefully crafted façade.