Kim Ha Yeon is an ordinary 18-year-old girl who dreams of a life as dramatic as the ones she sees on screen. Her life takes an unexpected, mystical turn when she heads to the unfamiliar countryside village of Upo-ri for her summer break. There, she crosses paths with Jo Yu Gyeom, the heir to a traditional noble family, and his girlfriend, Sae Ryeong. While he possesses stunning looks and a genius talent for swimming, he lives a colorless existence constrained by old-fashioned rules and repetitive routines. As these two opposites meet in the quiet beauty of Upo-ri, their worlds collide, sparking a transformation in their daily lives and the beginning of a once-in-a-lifetime summer.