Gang Nam-soon disappeared in Mongolia as a child. As an adult, she travels to South Korea to search for her parents where she finds her mother Hwang Geum-joo who is a billionaire businesswoman, and her grandmother Gil Joong-gan, in the Gangnam district. Eventually, Nam-soon, her mother, and grandmother become entangled in a drug case that Detective Gang Hee-sik is investigating at a company named Doogo ran by Ryu Shi-oh.