Eun Ha-Won, a college student with aspirations of becoming a veterinarian, is a bright young woman who feels lonely and disconnected from her family. After her mother’s tragic death in a car accident, she lives with her father, stepmother, and stepsister. One day, she assists an enigmatic elderly man who, in return, offers her the opportunity to live in a mansion and follow her dream of becoming a veterinarian. Accepting his offer, she moves into the mansion, where she resides with three cousins—Kang Ji-Woon, Kang Hyun-Min, and Kang Seo-Woo—and their bodyguard, Lee Yoon-Sung.