The Threshold of Death.

Dong-jin works at the immigration office, detecting illegal immigrants and entrants. He rarely meets his father, who has Alzheimer's disease, and it's awkward for him to meet his brother, Dong-seok, and his family. Nam-il, a colleague, uses his position to commit corruption and the youngest, Eun-seong, is too compassionate. One day, Dong-jin meets an ethnic Korean call girl named Yeon-hwa and starts to like her. She gets a call from a broker that he's withholding her niece, Soon-bok, who escaped from the North. Looking at Yeon-hwa and Soon-bok's sadness and innocent lives, Dong-jin's life begins to change. His father dies and Yeon-hwa kills herself. Dong-jin tries his best to save Soon-bok. He risks everything for her, but his efforts become worthless when Nam-il frames him for his irregularities and Eun-seong betrays him to protect their own family. Dong-jin loses everything and is left only with his search for Soon-bok.