Musical prodigy Cha Yoo-jin 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 Nae-il, a nutty classmate who eschews the rules and plays everything by ear, from music to life. Though initially repelled by her unrefined ways, Yoo-jin slowly discovers Nae-il is the unique melody to his harmony: combined, the two create a song that makes their hearts soar.