For the Sake of Son

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, marred 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.