Musical prodigy Cha Yoojin dreams of conducting orchestras, but despite his ambitions and international upbringing, he's begrudgingly stuck in South Korea because of a traumatic childhood accident. Cue Seol Naeil, a nutty classmate who eschews the rules and plays everything by ear, from music to life. Though initially repelled by her unrefined ways, Yoojin slowly discovers Naeil is the unique melody to his harmony: combined, the two create a song that makes their hearts soar.