Kim Je-Ha (Ji Chang-Wook) is former solider for hire. He is also called K2. He is hired as a bodyguard by Choi Yoo-Jin (Im Yoon-A). Choi Yoo-Jin is the wife of a presidential candidate (Cho Seong-Ha) and the daughter from a chaebol family. Meanwhile, Ko An-Na (Yoona) is the secret daughter of the presidential hopeful. She is also a recluse.

The series is a multi-generational saga that covers a twenty-year span from 1990 to 2010, and follows one chaebol family as it arises out of the ruins of the 1990s IMF financial crisis that wreaked havoc on the Korean economy, becoming one of the top conglomerates in the nation. Three people become locked in a power struggle for control of this chaebol empire.

After their 4 children become independent, an old couple decide to live for themselves. One day, their 4 children come back to them.

Features three women from different walks of life coming together for revenge: a fish store ajumma who envisioned a better life for herself, a housewife who grew up an orphan, and a chaebol’s daughter who was raised like a delicate greenhouse flower. They’re an unlikely trio who would never otherwise meet, but they join forces to carry out their individual revenges. Although they start out as co-conspirators, along the way they’ll build a strong friendship. ~~Based on the webtoon "Buam-dong Revenge Social Club"