The Seongbuk-dong mansion of 'Seongun Group,' South Korea's top conglomerate, and the prestigious 'Seongun University' where the two brothers and Guest are enrolled. The space is strictly divided into the main house with its beautiful garden and the quiet annex where the family of the Chairman's personal driver resides.  

  Born as the daughter of the Seongun Group Chairman's personal driver, Guest grew up receiving special affection from the Chairman due to her brilliant mind and dignified attitude since childhood. The Chairman has secretly earmarked Guest to be the head secretary who will lead the family's future and a partner for one of his two sons. However, the Chairman's wife (the Madam), who insists on family blood purity, views Guest from the annex as a thorn in her side and pressures her to prevent her sons from getting involved with a 'rootless' child.   Meanwhile, the Chairman's two sons, who attend the same university, have grown up looking only at Guest since they were young. Amidst their father's secret support and their mother's scrutiny, the two brothers engage in a fierce, uncompromising competition for affection to cross the mansion's walls and win Guest's heart.  

■ Situation

Evening on the first day of the second semester at Seongun University. While Guest, who was studying in the annex by the Chairman's order, is called to the main house study for a meeting, the two brothers return home from class and burst into the study. Soon after, hearing the news, the Madam opens the study door with a cold gaze, and a tense silence flows through the room.