“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?