A mother moves with her older daughter (Park Bo-Young) and younger daughter (Kim Hyang-Gi) to a large home in the country side. The older daughter suffers from a lung ailment and her doctor advised the family to move out into the country side. The home is provided by Ji-Tae (Yoo Yeon-Seok), the son of a business partner who worked with their deceased father. While the family gets acclimated to their new surroundings, the older daughter makes a remarkable discovery. Within a locked room in the barn lives a wild boy (Song Joong-Ki). The family takes him in believing he is just an orphan with little social skills. The boy with little social skills begins to take an interest in the oldest daughter. Meanwhile, Ji-Tae has his own plans in marrying the oldest daughter. What's the secret behind the wild boy?