Ji Sook is sent to South Korea to take her husband Tae Soo back o North Korea. Tae Soo is an agent of the South Korea National Intelligence Service. 15 years ago, Tae Soo infiltrated North Korea, married Ji Sook, and had a son. He then returned to South Korea, leaving behind Ji Sook and their son. Ji Sook and her son were then sent to a forced labor camp due to her husband's actions. High-ranking North Korean officials trained Ji Sook and sent her to South Korea to carry out a mission. Her mission is to persuade Tae Soo to go back to North Korea. Ji Sook's son is held as a hostage.
Meanwhile, Sung Ho is a detective, who has a son. He lost his wife 10 years ago. One day, Sung Ho and his son eat at a small neighborhood restaurant they often frequent. Sung Ho and his son talk about who will do household chores and the restaurant owner suggests someone that can do the chores. At first, Sung Ho says no, but then he sees Ji Sook walk into the restaurant. Sung Ho falls in love with her at first sight. Sung Ho asks the restaurant owner if Ji Sook is the woman who can do the household chores. The restaurant owner replies yes. Sung Ho decides to hire Ji Sook at that moment. Sung Ho has no idea that Ji Sook and the restaurant owner are North Korean spies and they approached him on purpose.