A promising pianist in a slump has a chance meeting with a young woman playing mysterious music, and the encounter forces him to make a once-in-a-lifetime choice.
Unfortunately the movie Secret: Untold Melody is not yet available on HBO Max.
| Directing | Seo You-min | Director |
| Writing | Jay Chou | Original Film Writer |
| Writing | Christine To Chi-Long | Original Film Writer |
| Camera | Yang Hyun-suk | Director of Photography |
| Editing | Kim Hyung-joo | Editor |
| Writing | Yoo Seung-hee | Writer |
| Writing | Shin Eun-kyung | Writer |
| Production | Choi Pyung-ho | Executive Producer |
| Production | William Kim | Producer |
| Production | Chung Hae-suk | Co-Executive Producer |
| Production | Kim Hwan-chul | Co-Executive Producer |
| Production | Patrick Park | Line Producer |
| Art | Kim Min-hye | Production Design |
| Art | Jeong Yi-jin | Conceptual Design |
| Sound | Park Yong-ki | Sound Supervisor |
| Sound | Cho Min-ho | Sound Recordist |
| Visual Effects | Jeon Min-gyu | Visual Effects Supervisor |
| Editing | Park Hyun-jin | Digital Intermediate |
| Costume & Make-Up | Seong So-won | Makeup & Hair |
| Costume & Make-Up | Hong Soo-hee | Costume Design |
| Costume & Make-Up | Seo Eun-kyung | Costume Design |
| Sound | Kim Jun-seong | Original Music Composer |
| Sound | Kim Ji-ae | Original Music Composer |
| Writing | Seo You-min | Writer |
| Sound | Jay Chou | Songs |
