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.