The Promise (2016)

Na-Yeon is a bright woman. She supports her boyfriend Tae-Joon, who is from a poor background. Even though they have a daughter, Tae-Joon dumps her for his own success and goes with Se-Jin. Se-Jin is the granddaughter of the President of Baekdoo Company.

Do-Hee is Na-Yeon’s twin sister. They have been separated since Do-Hee was adopted by a wealthy couple when she was an infant. Do-Hee now works as a reporter for a weekly magazine. For a story, Do-Hee investigates into the background of Tae-Joon. She discovers that she has a twin sister and Na-Yeon was dumped by Tae-Joon. Do-Hee also learns that Tae-Joon's mother got Na-Yeon hospitalized at a psychiatric hospital. Do-Hee visits Na-Yeon at the hospital, but a fire engulfs the hospital and Do-Hee dies. Na-Yeon then takes the identity of her twin sister.