Eun Ha-Won (Park So-Dam) is in the third grade of high school. She hopes to become a teacher which her late mother always wished for (her mother died in a car accident). Ha-Won has a bright personality and a strong set of morals, but she is unhappy at home. She's unattached from her father, step-mother and step-sister and also mistreated. Ha-Won works various part-time jobs to pay for her upcoming university tuition fees. She knows she needs to make more money to pay for the storage of her mother's ashes at the cemetery. Her mother's ashes were recently removed because of unpaid bills.
Meanwhile, Ji-Woon (Jung Il-Woo), Hyun-Min (Ahn Jae-Hyeon) and Seo-Woo (Lee Jung-Shin) are spoiled cousins and live together in the mansion Sky House. With their different personalities - Ji-Woon is a tough guy, Hyun-Min is a playboy and Seo-Woo is a musician - they don't like each other at all. Additionally, Ji-Woon likes Hye-Ji (Son Na-Eun) who likes Hyun-Min.
One day, their grandfather (Kim Yong-Geon) orders his 3 grandsons to attend his 5th wedding ceremony. Hyun-Min doesn't want to go, but he hires Ha-Won for 3 hours and takes her to his grandfather's wedding ceremony. His plan is to upstage his grandfather's wedding ceremony with the surprise appearance of Ha-Won. There, the grandfather witnesses Ha-Won's no-nonsense attitude towards Hyun-Min and decides to hire her as a live-in butler at the Sky House. He hopes she is able to change the ways of his grandsons.