“Secret Playlist” depicts the secret romance between Song Han Ju, an ordinary college student who secretly works as a music YouTuber, and Lee Do Guk, a member of the popular idol group SEZ who goes by the stage name Levi.

An ordinary 24-year-old college student, Han Joo. On the surface, she appears to be a hardworking job seeker facing the harsh reality, but secretly, she nurtures her dream of becoming a singer by operating a cover song SNS account called 'Plii,' all while keeping her identity hidden.

On the other hand, there's a member of the popular idol group S.E.Z., Do Gook. Approaching the end of his contract, he decides to seek out Plii, whom he has admired, for a collaboration project as he prepares to go solo. However, it turns out that the two were classmates in college! Han Joo, who must conceal her identity as Plii, and Do Gook, who needs to find Plii. Can they really uncover each other's true identities?

스물 네살의 평범한 여대생 ‘한주’. 겉보기엔 팍팍한 현실의 취준생이지만, 실은 ‘플리’라는 커버곡 SNS 계정을 운영하며 신상정보를 숨긴 채 은밀하게 가수의 꿈을 키워오고 있다. 한편 인기 아이돌 그룹 세즈의 멤버 ‘도국’. 계약 종료 시점을 앞두고 홀로서기를 준비하던 중 콜라보 작업을 위해 평소 동경하던 플리를 찾아내기로 결심한다. 그런데 알고보니 대학교 같은 과 동기였던 두 사람! 자신이 플리임을 숨겨야 하는 한주와, 플리를 찾아야하는 도국. 두 사람은 과연 서로의 정체를 알아챌 수 있을까?